Laser eye surgery system calibration

ABSTRACT

A laser system is calibrated with a tomography system capable of measuring locations of structure within an optically transmissive material such as a tissue of an eye. Alternatively or in combination, the tomography system can be used to track the location of the eye and adjust the treatment in response to one or more of the location or an orientation of the eye. In many embodiments, in situ calibration and tracking of an optically transmissive tissue structure such as an eye can be provided. The optically transmissive material may comprise one or more optically transmissive structures of the eye, or a non-ocular optically transmissive material such as a calibration gel in a container or an optically transmissive material of a machined part.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to U.S. provisional application No.61/888,065, filed on Oct. 8, 2013, the entire contents of which areincorporated herein by reference.

BACKGROUND

The present disclosure relates generally to photodisruption induced by apulsed laser beam and the location of the photodisruption so as to treata material, such as a tissue of an eye. Although specific reference ismade to cutting tissue for surgery such as eye surgery, embodiments asdescribed herein can be used in many ways with many materials to treatone or more of many materials, such as cutting of optically transparentmaterials.

Cutting of materials can be done mechanically with chisels, knives,scalpels and other tools such as surgical tools. However, prior methodsand apparatus of cutting can be less than desirable and provide lessthan ideal results in at least some instances. For example, at leastsome prior methods and apparatus for cutting materials such as tissuemay provide a somewhat rougher surface than would be ideal. Pulsedlasers can be used to cut one or more of many materials and have beenused for laser surgery to cut tissue.

The prior methods and apparatus to incise tissue with laser beams can beless than ideal in at least some instances. For example, the laser beammay not incise tissue at the target location, and the actual location ofthe laser beam incision may vary from the targeted position. Althoughcalibration can be used to improve the accuracy of the prior lasersurgery systems, calibration can be time consuming and the alignment ofthe system components may drift over time so as to require additionalcalibration in at least some instances. Also, the prior methods andapparatus of calibrating laser systems can be less than ideal. Forexample, after calibration of the laser system, the targeted incisionlocation can vary from the actual location of the incision.

In light of the above, it would be desirable to have improved methodsand apparatus of treating materials with laser beams, such as thesurgical cutting of tissue to treat cataracts and refractive errors ofthe eye. At least some of the above deficiencies of the prior methodsand apparatus are overcome by the embodiments described herein.

SUMMARY

Embodiments as described herein provide improved treatment of materialssuch as tissue. In many embodiments, a laser system is calibrated with atomography system capable of measuring locations of structure within anoptically transmissive material such as a tissue of an eye.Alternatively or in combination, the tomography system can be used totrack the location of the eye and adjust the treatment in response toone or more of the location or an orientation of the eye. In manyembodiments, in situ calibration and tracking of an opticallytransmissive tissue structure such as an eye can be provided. Theoptically transmissive material may comprise one or more opticallytransmissive structures of the eye, or a non-ocular opticallytransmissive material such as a calibration gel in a container or anoptically transmissive material of a machined part. In many embodiments,the one or more target locations comprises a plurality of targetlocations and the one or more marks comprises a plurality of marks, andeach of the plurality of marks is identified has having a correspondingtarget location. The plurality of marks can be distributed so as todefine a three dimensional volume in order to improve accuracy, and inmany embodiments the three dimensional volume comprises a plurality ofmaterials, each having a different index of refraction. As thetomography system may comprise one or more wavelengths different fromthe laser treatment system, the calibration and eye tracking can bothprovide improved accuracy for target tissue structures identified andmeasured with the tomography system. In many embodiments, the volumecomprises a plurality of tissue structures in which each tissuestructure comprises a different index of refraction for the tomographybeam and the measurement beam. The measurement of the location of eachmark and comparison with the corresponding target location for aplurality of locations of the volume can provide substantially improvedaccuracy, such as when the volume comprises the plurality of tissuestructures having different indices of refraction.

In many embodiments, a laser system is calibrated in response tomeasured locations of the one or more marks. In many embodiments, adifference between the measured location and the corresponding targetlocation and is determined for each of the plurality of marks so as todetermine calibration of the laser eye surgery system. Machineparameters of the laser eye surgery system can be adjusted to as tocorrect errors of the plurality of marks and the corresponding targetlocations. The machine parameters may comprise one or more ofcalibration coefficients, values of look up tables, coefficients ofpolynomials, or mapping parameters to map from a target location of aneye coordinate reference system to a machine coordinate referencesystem.

Alternatively or in combination with calibration, the locations of themarks can be measured to determine movement of the eye. The location ofone or more marks can be compared with prior locations of the one ormore marks and the locations of the laser beam pulses adjusted inresponse to the measured locations. In many embodiments, each of themeasured locations is compared with a reference location such as atarget location or a prior location of the mark. In many embodiments,the locations of the plurality of marks are used to determine movementof the eye, rotational movement or translational movement, or both. Inmany embodiments, the one or more locations comprises a plurality ofmeasured locations of the marks in order to determine the rotational andtranslational movement of the eye. The locations of the plurality ofpoints can be used to determine rotation and translation of the eye inrelation to the eye coordinate reference system to adjust the locationsof the laser beam pulses. In many embodiments, the rotation around oneor more axes of the eye and the translation along one or more axis ofthe eye can be used to adjust the target locations of the laser beampulses. In many embodiments, the plurality of marks comprises three ormore marks and the rotational and translational movement of the eye inrelation to each of three dimensions of the eye determined, so as tocorrect for three translational degrees of freedom of the eye and threerotational degrees of freedom of the eye. In many embodiments, the eyecomprises a plurality of tissue structures each having a different indexof refraction, and the targeted locations of the eye can be adjusted inresponse to locations of the tissue structures having the differentindices of refraction

An aspect of the disclosure provides a laser system to treat an objectwith a laser beam. The laser system comprises a laser, a tomographysystem, an optical delivery system, and a processor. The laser generatesthe laser beam. The tomography system generates a measurement beam andmeasures an optically transmissive material of the object. The opticaldelivery system is coupled to the laser and the tomography system todeliver the laser beam and the measurement beam to the object. Theprocessor is coupled to the laser, the tomography system, and theoptical delivery system. The processor comprises a tangible mediumembodying instructions to place a mark on the object with the laser beamin response to a target location and measure a location of the mark withthe measurement beam.

The object to be treated with the laser beam may comprise one or more ofan eye, an optically transmissive material, a gel, a liquid, a viscousmaterial, a solid optically transmissive material, or a fluid of apatient interface above the eye. The fluid of the patient interface maycomprise one or more of saline or viscoelastic fluid. The fluid may bemarked with the laser beam.

The processor may comprise instructions to mark the eye at a pluralityof locations corresponding to a plurality of target locations. Theplurality of locations may comprise locations of one or more of acornea, an aqueous humor, an iris, an anterior lens capsule, an anteriorlens capsule, a posterior lens capsule, a cortex, or a nucleus. Theprocessor may comprise instructions to mark the eye at the plurality oflocations prior to incising the eye with a plurality of laser beampulses to one or more of incise or treat the eye with the laser beampulses. The plurality of marks can define a volume and laser beam pulsesto incise the tissue can be delivered at a plurality of locations withinthe volume. The processor may further comprise instructions to identifya corresponding target location for each of the plurality of marksmeasured with the tomography system. The processor may comprisesinstructions to compare the corresponding target location with measuredlocation for each of the plurality of marks in order to determine one ormore of calibration or eye position. The volume may comprise at least aportion of a tissue structure of the eye comprising one or more of atear film, a cornea, an aqueous humor, an iris, an anterior lenscapsule, the posterior lens capsule, a lens cortex, a lens nucleus, avitreous humor, a Berger's space or an anterior hyaloid membrane of thevitreous. The tissue structure of the eye may comprise a plurality oftissue structures. Each of the plurality of tissue structures may have adifferent index of refraction for the laser beam than another of theplurality of tissue structures. Each tissue structure may comprise afirst index of refraction for the laser beam and a second index ofrefraction for a measurement beam of the tomography system. The firstindex of refraction may be different from the second index ofrefraction. The laser beam and measurement beam may comprise one or morewavelengths of light different from each other.

The processor may further comprise instructions to compare the locationof the mark with the target location and calibrate the laser in responseto the location of the mark and the targeted location of the mark. Theprocessor may comprise instructions to perform in situ calibration tocorrect for drift of an optical delivery system to deliver the laserbeam to the object. The processor may comprise instructions to perform adaily calibration to correct for drift of an optical delivery system todeliver the laser beam to the object. The processor may comprisesinstructions to adjust one or more machine parameters related to one ormore of the laser, the optical delivery system, or the tomography systemin response to a comparison of the corresponding target location withmeasured location for said each of the plurality of marks in order tocalibrate the laser system.

The processor may comprise instructions to track the object in responseto the measured location of the mark. The processor may compriseinstructions to adjust positions of the laser beam pulses in response toa comparison of the corresponding target location with measured locationfor said each of the plurality of marks in order to track and correctfor eye movement with the laser system. The location of each of theplurality of marks can be compared with a prior location of said each ofthe plurality of marks in order to determine movement of the eye. Theplurality of marks may comprise three or more marks. The movement of theeye may comprise rotation of the eye around one or more dimensions of acoordinate reference system of the eye. The treatment can be adjusted inresponse to translation along the one or more dimensions. The movementof the eye can comprise translation of the eye along one or moredimensions of the coordinate reference system of the eye. The treatmentcan be adjusted in response to translation along the one or moredimensions. The one or more dimensions may comprise three dimensions.The treatment can be adjusted in response to rotation around the threedimensions and translation along the three dimensions. The opticallytransmissive material may comprise a plurality of optically transmissivestructures having a plurality of indices of refraction. Positions oflaser beam pulses to treat one or more of the optically transmissivestructures can be adjusted in response to locations of the opticallytransmissive structures having the plurality of indices of refraction.The processor can comprise instructions to mark the material in each ofthe optically transmissive structures to define a volume comprising theplurality of optically transmissive structures having the plurality ofindices of refraction. The processor can comprises instructions to markthe material in a first of the optically transmissive structures and toadjust positions of the laser beam pulses for treatment in a second ofthe optically transmissive structures without placing marks for trackingin the second of the optically transmissive structures. The second ofthe plurality of optically transmissive structures can comprise an indexof refraction different than the index of refraction of the first of theoptically transmissive structures.

The processor can comprise instructions to mark the material with one ormore bubbles. The processor can comprise instructions to correct foroptical aberrations in response to locations of the one or more bubbles.

The tomography system can comprise one or more of an optical coherencetomography system, a spectral domain optical coherence tomographysystem, a time domain optical coherence tomography system, a Scheimpflugtomography system, a confocal tomography system, or a low coherencereflectometry system.

The laser system may further comprise an acoustic transducer to detectoptical breakdown in response to an amount of energy of the laser beam.

Another aspect of the disclosure provides a method of treating an objectwith a laser beam. A mark is placed on the object in response to atarget location. A location of the mark is measured with a measurementbeam. The laser beam can be generated by a laser and delivered by anoptical delivery system. The measurement beam can be generated by atomography system and delivered by an optical delivery system.

The tomography system may comprise one or more of an optical coherencetomography system, a spectral domain optical coherence tomographysystem, a time domain optical coherence tomography system, a Scheimpflugtomography system, a confocal tomography system, or a low coherencereflectometry system.

The object to be treated may comprise one or more of an eye, anoptically transmissive material, a gel, a liquid, a viscous material, asolid optically transmissive material, or a fluid of a patient interfaceabove the eye. The fluid of the patient interface may comprise one ormore of saline or viscoelastic fluid. The fluid may be marked with thelaser beam.

Placing the mark on the object in response to a target location maycomprise marking the eye at a plurality of locations corresponding to aplurality of target locations. The plurality of locations may compriselocations of one or more of a cornea, an aqueous humor, an iris, ananterior lens capsule, an anterior lens capsule, a posterior lenscapsule, a cortex or a nucleus. The eye may further be incised with aplurality of laser beam pulses to one or more of incise or treat the eyewith the laser beam pulses subsequent to placing the mark on the object.The eye may be marked at the plurality of location to define a volume.The volume may comprise at least a portion of a tissue structure of theeye comprising one or more of a tear film, a cornea, an aqueous humor,an iris, an anterior lens capsule, the posterior lens capsule, a lenscortex, a lens nucleus, a vitreous humor, a Berger's space or ananterior hyaloid membrane of the vitreous humor. Laser beam pulses toincise the tissue can be delivered at a plurality of locations withinthe volume. A corresponding target location for each of the plurality ofmarks measured with the tomography system can be identified. Thecorresponding target location can be compared with the measured locationfor each of the plurality of marks in order to determine one or more ofcalibration or eye position. The tissue structure of the eye maycomprise a plurality of tissue structures. Each of the plurality oftissue structures may have a different index of refraction for the laserbeam than another of the plurality of tissue structures. Each tissuestructure may comprise a first index of refraction for the laser beamand a second index of refraction for a measurement beam of thetomography system. The first index of refraction may be different fromthe second index of refraction. The laser beam and measurement beam maycomprise one or more wavelengths of light different from each other.

Further, the location of the mark may be compared with the targetlocation and the laser can be calibrated in response to the location ofthe mark and the targeted location of the mark. In situ calibration canbe performed to correct for drift of an optical delivery system todeliver the laser beam to the object. A daily calibration can beperformed to correct for drift of an optical delivery system to deliverthe laser beam to the object. One or more machine parameters related toone or more of the laser, the optical delivery system, or the tomographysystem can be adjusted in response to a comparison of the correspondingtarget location with measured location for said each of the plurality ofmarks in order to calibrate the laser system.

Further, the object can be tracked in response to the measured locationof the mark. The positions of the laser beam pulses can be adjusted inresponse to a comparison of the corresponding target location withmeasured location for said each of the plurality of marks in order totrack and correct for eye movement with the laser system. The locationof each of the plurality of marks can be compared with a prior locationof said each of the plurality of marks in order to determine movement ofthe eye. The plurality of marks can comprise three or more marks. Themovement of the eye can comprise rotation of the eye around one or moredimensions of a coordinate reference system of the eye. The treatmentcan be adjusted in response to translation along the one or moredimensions. The movement of the eye may comprise translation of the eyealong one or more dimensions of the coordinate reference system of theeye. The treatment can be adjusted in response to translation along theone or more dimensions. The one or more dimensions may comprise threedimensions and the treatment can be adjusted in response to rotationaround the three dimensions and translation along the three dimensions.

The optically transmissive material may comprise a plurality ofoptically transmissive structures having a plurality of indices ofrefraction. The positions of laser beam pulses to treat one or more ofthe optically transmissive structures can be adjusted in response tolocations of the optically transmissive structures having the pluralityof indices of refraction. The material in each of the opticallytransmissive structures can be marked to define a volume comprising theplurality of optically transmissive structures having the plurality ofindices of refraction. The material in a first of the opticallytransmissive structures can be marked and the positions of the laserbeam pulses can be adjusted for treatment in a second of the opticallytransmissive structures without placing marks for tracking in the secondof the optically transmissive structures. The second of the plurality ofoptically transmissive structures can comprise an index of refractiondifferent than the index of refraction of the first of the opticallytransmissive structures.

The material may be marked with one or more bubbles and opticalaberrations can be corrected for in response to locations of the one ormore bubbles.

Optical breakdown can be detected in response to an amount of energy ofthe laser beam with an acoustic transducer.

Additional aspects are provided in the claims below, and incorporatedherein by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view showing a laser eye surgery system, inaccordance with many embodiments;

FIG. 2 shows a simplified block diagram showing a top level view of theconfiguration of a laser eye surgery system, in accordance with manyembodiments;

FIG. 3A shows a simplified block diagram illustrating the configurationof an optical assembly of a laser eye surgery system, in accordance withmany embodiments;

FIG. 3B shows a mapped treatment region of the eye comprising thecornea, the posterior capsule, and the limbus, in accordance with manyembodiments;

FIG. 3C shows mapped changes in beam focus for locations of the mappedtreatment region, in accordance with many embodiments;

FIG. 4A shows correspondence among movable and sensor components of thelaser delivery system, in accordance with many embodiments;

FIG. 4B shows mapping of coordinate references from an eye spacecoordinate reference system to a machine coordinate reference system, inaccordance with many embodiments;

FIG. 4C shows a feedback loop to adjust look up table calibrationmapping from a generalized system to a specific individual constructedsystem based on measurements of the individual constructed system, inaccordance with many embodiments;

FIG. 5 shows a method of calibration a laser system, in accordance withmany embodiments;

FIG. 6A shows an eye coordinate reference system referenced to a lowersurface of an optically transmissive structure of a patient interface,in accordance with many embodiments;

FIGS. 6B and 6C show side views and front views of structures of the eyeas in FIG. 6A coupled to the patient interface and the eye coordinatereference frame for mapping to the machine coordinate reference frame,in accordance with many embodiments;

FIG. 7A shows a look up table summary for an ultrafast laser, inaccordance with many embodiments;

FIG. 7A1 shows an optical schematic of the components corresponding tothe look up table summary of FIG. 7A;

FIG. 7A2 shows input and output of the look up table as in FIGS. 7A and7A1;

FIG. 7A3 shows structure and excerpt of a look up table as in FIGS. 7Ato 7A2;

FIG. 7B shows a look up table summary for an optical coherencetomography system, in accordance with many embodiments;

FIG. 7B1 shows an optical schematic of the components corresponding tothe look up table summary of FIG. 7B;

FIG. 7B2 shows input and output of the look up table as in FIGS. 7B and7B1

FIG. 7B3 shows structure and excerpt of the look up table as in FIGS. 7Bto 7B2;

FIG. 7C shows a look up table summary for a video camera, in accordancewith many embodiments;

FIG. 7C1 shows an optical schematic of the components corresponding tothe look up table of FIG. 7C;

FIG. 7C2 shows the input and output of the look up table as in FIGS. 7Cand 7C1

FIG. 7C3 shows structure and excerpt of the look up table as in FIGS. 7Cto 7C2;

FIGS. 8A and 8B show side and front views of structures of the eye thathave one or more markings for calibration, in accordance with manyembodiments;

FIGS. 8C and 8D show side and front views of structures of the eye thathave one or more markings for calibration corresponding to one or moretarget locations, in accordance with many embodiments;

FIGS. 9A and 9B show side and front views of structures of the eye thathave a plurality of markings for calibration, in accordance with manyembodiments;

FIGS. 9C and 9D show side and front views of structures of the eye thathave a plurality of markings for calibration corresponding to aplurality of target locations, in accordance with many embodiments;

FIGS. 10A and 10B show side and front views of structures of the eyethat have a plurality of markings that define a calibration volume, inaccordance with many embodiments;

FIGS. 11A and 11B show side and front views of structures of the eyethat have a plurality of markings in the viscous fluid in the eye, inaccordance with many embodiments;

FIGS. 12A and 12B show side and front views of a calibration apparatus,in accordance with many embodiments;

FIGS. 13A and 13B show side and front views of structures of the eyeincluding markings for tracking, in accordance with many embodiments;

FIGS. 13C and 13D show side and front views of structures of the eyeincluding markings that are tracked for movement, in accordance withmany embodiments;

FIG. 13E shows an coordinate reference system, in accordance with manyembodiments;

FIG. 14 shows a method of calibration a laser eye surgery system, inaccordance with many embodiments;

FIG. 15 shows a method of tracking the eye, in accordance with manyembodiments; and

FIG. 16 shows an empirical example of a method of calibration of a lasereye surgery system, in accordance with many embodiments.

DETAILED DESCRIPTION

Methods and systems related to laser eye surgery are disclosed. In manyembodiments, a laser is used to form precise incisions in the cornea, inthe lens capsule, and/or in the crystalline lens nucleus. Althoughspecific reference is made to tissue treatment for laser eye surgery,embodiments as described herein can be combined in one or more of manyways with many surgical procedures and devices, such as orthopedicsurgery, robotic surgery, and microkeratomes.

The embodiments as describe herein are particularly well suit fortreating tissue, such as with the surgical treatment of tissue. In manyembodiments, the tissue comprises an optically transmissive tissue, suchas tissue of an eye. The embodiments as described herein can be combinedin many ways with one or more of many known surgical procedures such ascataract surgery, laser assisted in situ keratomileusis (hereinafter“LASIK”), laser assisted sub-epithelial keratectomy (hereinafter“LASEK”). The embodiments as described herein are also particularly wellsuited for retinal surgery, for example.

The embodiments as described herein are particularly well suited forcalibrating laser surgery systems capable of providing a treatmentwithin a three dimensional volume, and the target locations and markscan be defined such that as least a portion of the treatment is withinthe three dimensional volume defined with the plurality of targetlocations.

In many embodiments, the laser eye surgery system comprises a processorhaving a tangible medium embodying instructions to track the location ofthe eye in response to marks of the eye provided with pulses of thelaser beam

The present disclosure provides methods and apparatus for providingadjustment to compensate for variations in disposable elements and otherattachments, tolerances in hardware and alignment, and patient anatomy.The methods and apparatus may comprise closed loop control combined withsoftware calibration parameters such a calibration coefficients, or asoftware look up table (hereinafter “LUT”) embodied in a tangiblemedium. The LUT may generalize a regression network, a neural network,splines, and the like. The closed loop control may comprise marking theeye at a targeted location, measuring the location of the mark with atomography system, and correcting for the location with subsequent laserbeam pulses for improved calibration or eye-tracking, and combinationsthereof, for example.

The LUT may comprise a map of locations of the cutting volume in orderto the control of actuators that direct the ranging (target detection)and the cutting modalities. A baseline LUT can be generated for ageneralized system using optical based rules and physics, detailedmodeling of components, and anchoring (one time) to a finite data set asdescribed herein. The expected variations can be reduced into a set offinite and manageable variables that are applied to modify the tablessubsequent to the original generation of the tables. For a constructedsystem having constructed components with manufacturing tolerances, finetuning and modification of the LUTs can be achieved thru simplemodifications of the tables based on individual system and automatedmeasurements. These individualized measurements of a constructed systemcan be applied to variations due to one or more of: tool-to-toolvariation, tool to itself variation (for example align variations),output attachment variations (for example disposable contact lenses), orpatient to patient (for example individual patient anatomy), andcombinations thereof, for example.

In many embodiments, one or more of the following steps can be performedwith the processor and methods as described herein. For example,baseline LUT generation can be performed comprising mapping and positiondetection in order to provide actuator commands to evaluate systemoutput performance. A baseline transfer function can be generated for apatient coordinate reference system such as XYZ to detect actuators ofthe system, for example. Baseline LUT generation can be performed to mapcutting to actuators. A transfer function can be generated for XYZ tocutting actuators, for example. Baseline LUTs (transfer functions) canbe generated via model (ray trace), data, or a combination, for example.The baseline LUTs can be modified given variations in the system,disposable, eye, and/or application, for example. The baseline LUTmodification may comprise an adjustment to the baseline LUT, forexample. The baseline LUT modification may comprise a software(hereinafter “SW”) adjustment to compensate for hardware (hereinafter“HW”) variations, for example. The LUT modification as described hereincan extend surgical volume, so as to treat the cornea, the limbus andthe posterior capsule, either in lateral extent, axial extent, andresolution, for example. The LUT methods and apparatus can enableswitching in tools for calibration and other optical components toaccessorize—output attachments, for example. The LUT can be set up sothat the system is capable of measuring location of attachments at twosurfaces and then can accurately place cuts in targeted material volumebased on modifying the baseline LUT using this the locations of the twosurfaces, for example. The LUTS can provide more cuts ranging from lens,capsule, corneal incisions for cataract, cornea flaps, for example. Thedifferent sub-systems as described herein can have separate LUTS, whichcan be combined with calibration process as described herein, forexample.

Alternatively, or in combination, the same sub-system can be used forboth ranging and cutting, for example. The UF system can be used at alow power level to find surfaces and then used at high power forcutting, for example. The LUTs can be used such that the location modediffers from the cutting mode. For example, the cut locations can differbased on changes with power level. The cut location may not occur atfocus, for example when the energy per pulse substantially exceeds thethreshold amount of energy, for example.

In many embodiments, the LUTs of the methods and apparatus as describedherein follow these principles. The baseline LUT can generated by raytracing and data anchoring using specific tooling, for example. In manyembodiments, each optically transmissive structure of the patientinterface, for example a lens, is read by the system to determine itsthickness and location. These numbers can be used to modify the LUTS toattain <100 um accuracy, for example.

In many embodiments, the LUTs of the methods and apparatus as describedherein are also modified to account for alignment tilts, contact lensmounting, contact lens variations so as to achieve <100 um accuracy oncuts, for example. In many embodiments, bubbles in plastic flatness testwith the calibration apparatus as described herein generates offset andtilt adjustments of baseline UF LUT.

In many embodiments, the baseline component specifications may be lessthan ideal for delivering an appropriate system performance, and thefinal performance can be refined using SW corrections and factors basedon the components of the individual system which can be determined fromoptically-grounded data-anchored baseline LUTs further modified forenhanced performance, for example.

A feedback loop can be used to build the enhanced or modified LUTs forthe individual laser system, for example. The feedback methods andapparatus as described herein can allow SW adjustments based on LUTs andother SW factors that may not be corrected with hardware alignment, forexample.

The LUTs and the methods an apparatus configured to modify the look uptables so as to enhance system performance can provide an improvementwithin the 3D surgical volume as described herein. The methods andapparatus as described herein can provide improved surgery for morepatients with a level of high performance. The methods and apparatus asdescribed herein can provide high performance using off-the-shelfcomponents, such as high volume low cost components, such that thesurgical procedures as described herein can be available to manypatients.

As used herein, the terms anterior and posterior refers to knownorientations with respect to the patient. Depending on the orientationof the patient for surgery, the terms anterior and posterior may besimilar to the terms upper and lower, respectively, such as when thepatient is placed in a supine position on a bed. The terms distal andanterior may refer to an orientation of a structure from the perspectiveof the user, such that the terms proximal and distal may be similar tothe terms anterior and posterior when referring to a structure placed onthe eye, for example. A person of ordinary skill in the art willrecognize many variations of the orientation of the methods andapparatus as described herein, and the terms anterior, posterior,proximal, distal, upper, and lower are used merely by way of example.

As used herein, the terms first and second are used to describestructures and methods without limitation as to the order of thestructures and methods which can be in any order, as will be apparent toa person of ordinary skill in the art based on the teachings providedherein.

As used herein light encompasses electromagnetic radiation having one ormore wavelengths in one or more of the ultraviolet, visible or infraredportions of the electromagnetic spectrum.

As used herein in situ encompasses in position and refers tomeasurements and treatments made with an object located in substantiallythe same position.

FIG. 1 shows a laser eye surgery system 2, in accordance with manyembodiments, operable to form precise incisions in the cornea, in thelens capsule, and/or in the crystalline lens nucleus. The system 2includes a main unit 4, a patient chair 6, a dual function footswitch 8,and a laser footswitch 10.

The main unit 4 includes many primary subsystems of the system 2. Forexample, externally visible subsystems include a touch-screen controlpanel 12, a patient interface assembly 14, patient interface vacuumconnections 16, a docking control keypad 18, a patient interface radiofrequency identification (RFID) reader 20, external connections 22(e.g., network, video output, footswitch, USB port, door interlock, andAC power), laser emission indicator 24, emergency laser stop button 26,key switch 28, and USB data ports 30.

The patient chair 6 includes a base 32, a patient support bed 34, aheadrest 36, a positioning mechanism, and a patient chair joystickcontrol 38 disposed on the headrest 36. The positioning controlmechanism is coupled between the base 32 and the patient support bed 34and headrest 36. The patient chair 6 is configured to be adjusted andoriented in three axes (x, y, and z) using the patient chair joystickcontrol 38. The headrest 36 and a restrain system (not shown, e.g., arestraint strap engaging the patient's forehead) stabilize the patient'shead during the procedure. The headrest 36 includes an adjustable necksupport to provide patient comfort and to reduce patient head movement.The headrest 36 is configured to be vertically adjustable to enableadjustment of the patient head position to provide patient comfort andto accommodate variation in patient head size.

The patient chair 6 allows for tilt articulation of the patient's legs,torso, and head using manual adjustments. The patient chair 6accommodates a patient load position, a suction ring capture position,and a patient treat position. In the patient load position, the chair 6is rotated out from under the main unit 4 with the patient chair back inan upright position and patient footrest in a lowered position. In thesuction ring capture position, the chair is rotated out from under themain unit 4 with the patient chair back in reclined position and patientfootrest in raised position. In the patient treat position, the chair isrotated under the main unit 4 with the patient chair back in reclinedposition and patient footrest in raised position.

The patient chair 6 is equipped with a “chair enable” feature to protectagainst unintended chair motion. The patient chair joystick 38 can beenabled in either of two ways. First, the patient chair joystick 38incorporates a “chair enable” button located on the top of the joystick.Control of the position of the patient chair 6 via the joystick 38 canbe enabled by continuously pressing the “chair enable” button.Alternately, the left foot switch 40 of the dual function footswitch 8can be continuously depressed to enable positional control of thepatient chair 6 via the joystick 38.

In many embodiments, the patient control joystick 38 is a proportionalcontroller. For example, moving the joystick a small amount can be usedto cause the chair to move slowly. Moving the joystick a large amountcan be used to cause the chair to move faster. Holding the joystick atits maximum travel limit can be used to cause the chair to move at themaximum chair speed. The available chair speed can be reduced as thepatient approaches the patient interface assembly 14.

The emergency stop button 26 can be pushed to stop emission of all laseroutput, release vacuum that couples the patient to the system 2, anddisable the patient chair 6. The stop button 26 is located on the systemfront panel, next to the key switch 28.

The key switch 28 can be used to enable the system 2. When in a standbyposition, the key can be removed and the system is disabled. When in aready position, the key enables power to the system 2.

The dual function footswitch 8 is a dual footswitch assembly thatincludes the left foot switch 40 and a right foot switch 42. The leftfoot switch 40 is the “chair enable” footswitch. The right footswitch 42is a “vacuum ON” footswitch that enables vacuum to secure a liquidoptics interface suction ring to the patient's eye. The laser footswitch10 is a shrouded footswitch that activates the treatment laser whendepressed while the system is enabled.

In many embodiments, the system 2 includes external communicationconnections. For example, the system 2 can include a network connection(e.g., an RJ45 network connection) for connecting the system 2 to anetwork. The network connection can be used to enable network printingof treatment reports, remote access to view system performance logs, andremote access to perform system diagnostics. The system 2 can include avideo output port (e.g., HDMI) that can be used to output video oftreatments performed by the system 2. The output video can be displayedon an external monitor for, for example, viewing by family membersand/or training. The output video can also be recorded for, for example,archival purposes. The system 2 can include one or more data outputports (e.g., USB) to, for example, enable export of treatment reports toa data storage device. The treatments reports stored on the data storagedevice can then be accessed at a later time for any suitable purposesuch as, for example, printing from an external computer in the casewhere the user without access to network based printing.

FIG. 2 shows a simplified block diagram of the system 2 coupled with apatient eye 43. The patient eye 43 comprises a cornea 43C, a lens 43Land an iris 43I. The iris 43I defines a pupil of the eye 43 that may beused for alignment of eye 43 with system 2. The system 2 includes acutting laser subsystem 44, a ranging subsystem 46, an alignmentguidance system 48, shared optics 50, a patient interface 52, controlelectronics 54, a control panel/GUI 56, user interface devices 58, andcommunication paths 60. The control electronics 54 is operativelycoupled via the communication paths 60 with the cutting laser subsystem44, the ranging subsystem 46, the alignment guidance subsystem 48, theshared optics 50, the patient interface 52, the control panel/GUI 56,and the user interface devices 58.

In many embodiments, the cutting laser subsystem 44 incorporatesfemtosecond (FS) laser technology. By using femtosecond lasertechnology, a short duration (e.g., approximately 10⁻¹³ seconds induration) laser pulse (with energy level in the micro joule range) canbe delivered to a tightly focused point to disrupt tissue, therebysubstantially lowering the energy level required as compared to thelevel required for ultrasound fragmentation of the lens nucleus and ascompared to laser pulses having longer durations.

The cutting laser subsystem 44 can produce laser pulses having awavelength suitable to the configuration of the system 2. As anon-limiting example, the system 2 can be configured to use a cuttinglaser subsystem 44 that produces laser pulses having a wavelength from1020 nm to 1050 nm. For example, the cutting laser subsystem 44 can havea diode-pumped solid-state configuration with a 1030 (+/−5) nm centerwavelength.

The cutting laser subsystem 44 can include control and conditioningcomponents. For example, such control components can include componentssuch as a beam attenuator to control the energy of the laser pulse andthe average power of the pulse train, a fixed aperture to control thecross-sectional spatial extent of the beam containing the laser pulses,one or more power monitors to monitor the flux and repetition rate ofthe beam train and therefore the energy of the laser pulses, and ashutter to allow/block transmission of the laser pulses. Suchconditioning components can include an adjustable zoom assembly to adaptthe beam containing the laser pulses to the characteristics of thesystem 2 and a fixed optical relay to transfer the laser pulses over adistance while accommodating laser pulse beam positional and/ordirectional variability, thereby providing increased tolerance forcomponent variation.

The ranging subsystem 46 is configured to measure the spatialdisposition of eye structures in three dimensions. The measured eyestructures can include the anterior and posterior surfaces of thecornea, the anterior and posterior portions of the lens capsule, theiris, and the limbus. In many embodiments, the ranging subsystem 46utilizes optical coherence tomography (OCT) imaging. As a non-limitingexample, the system 2 can be configured to use an OCT imaging systememploying wavelengths from 780 nm to 970 nm. For example, the rangingsubsystem 46 can include an OCT imaging system that employs a broadspectrum of wavelengths from 810 nm to 850 nm. Such an OCT imagingsystem can employ a reference path length that is adjustable to adjustthe effective depth in the eye of the OCT measurement, thereby allowingthe measurement of system components including features of the patientinterface that lie anterior to the cornea of the eye and structures ofthe eye that range in depth from the anterior surface of the cornea tothe posterior portion of the lens capsule and beyond.

The alignment guidance subsystem 48 can include a laser diode or gaslaser that produces a laser beam used to align optical components of thesystem 2. The alignment guidance subsystem 48 can include LEDs or lasersthat produce a fixation light to assist in aligning and stabilizing thepatient's eye during docking and treatment. The alignment guidancesubsystem 48 can include a laser or LED light source and a detector tomonitor the alignment and stability of the actuators used to positionthe beam in X, Y, and Z. The alignment guidance subsystem 48 can includea video system that can be used to provide imaging of the patient's eyeto facilitate docking of the patient's eye 43 to the patient interface52. The imaging system provided by the video system can also be used todirect via the GUI the location of cuts. The imaging provided by thevideo system can additionally be used during the laser eye surgeryprocedure to monitor the progress of the procedure, to track movementsof the patient's eye 43 during the procedure, and to measure thelocation and size of structures of the eye such as the pupil and/orlimbus.

The shared optics 50 provides a common propagation path that is disposedbetween the patient interface 52 and each of the cutting laser subsystem44, the ranging subsystem 46, and the alignment guidance subsystem 48.In many embodiments, the shared optics 50 includes beam combiners toreceive the emission from the respective subsystem (e.g., the cuttinglaser subsystem 44, and the alignment guidance subsystem 48) andredirect the emission along the common propagation path to the patientinterface. In many embodiments, the shared optics 50 includes anobjective lens assembly that focuses each laser pulse into a focalpoint. In many embodiments, the shared optics 50 includes scanningmechanisms operable to scan the respective emission in three dimensions.For example, the shared optics can include an XY-scan mechanism(s) and aZ-scan mechanism. The XY-scan mechanism(s) can be used to scan therespective emission in two dimensions transverse to the propagationdirection of the respective emission. The Z-scan mechanism can be usedto vary the depth of the focal point within the eye 43. In manyembodiments, the scanning mechanisms are disposed between the laserdiode and the objective lens such that the scanning mechanisms are usedto scan the alignment laser beam produced by the laser diode. Incontrast, in many embodiments, the video system is disposed between thescanning mechanisms and the objective lens such that the scanningmechanisms do not affect the image obtained by the video system.

The patient interface 52 is used to restrain the position of thepatient's eye 43 relative to the system 2. In many embodiments, thepatient interface 52 employs a suction ring that is vacuum attached tothe patient's eye 43. The suction ring is then coupled with the patientinterface 52, for example, using vacuum to secure the suction ring tothe patient interface 52. In many embodiments, the patient interface 52includes an optically transmissive structure having a posterior surfacethat is displaced vertically from the anterior surface of the patient'scornea and a region of a suitable liquid (e.g., a sterile bufferedsaline solution (BSS) such as Alcon BSS (Alcon Part Number 351-55005-1)or equivalent) is disposed between and in contact with the patientinterface lens posterior surface and the patient's cornea and forms partof a transmission path between the shared optics 50 and the patient'seye 43. The optically transmissive structure may comprise a lens 96having one or more curved surfaces. Alternatively, the patient interface22 may comprise an optically transmissive structure having one or moresubstantially flat surfaces such as a parallel plate or wedge. In manyembodiments, the patient interface lens is disposable and can bereplaced at any suitable interval, such as before each eye treatment.

The control electronics 54 controls the operation of and can receiveinput from the cutting laser subsystem 44, the ranging subsystem 46, thealignment guidance subsystem 48, the patient interface 52, the controlpanel/GUI 56, and the user interface devices 58 via the communicationpaths 60. The communication paths 60 can be implemented in any suitableconfiguration, including any suitable shared or dedicated communicationpaths between the control electronics 54 and the respective systemcomponents. The control electronics 54 can include any suitablecomponents, such as one or more processor, one or morefield-programmable gate array (FPGA), and one or more memory storagedevices. In many embodiments, the control electronics 54 controls thecontrol panel/GUI 56 to provide for pre-procedure planning according touser specified treatment parameters as well as to provide user controlover the laser eye surgery procedure.

The user interface devices 58 can include any suitable user input devicesuitable to provide user input to the control electronics 54. Forexample, the user interface devices 58 can include devices such as, forexample, the dual function footswitch 8, the laser footswitch 10, thedocking control keypad 18, the patient interface radio frequencyidentification (RFID) reader 20, the emergency laser stop button 26, thekey switch 28, and the patient chair joystick control 38.

FIG. 3A is a simplified block diagram illustrating an assembly 62, inaccordance with many embodiments, that can be included in the system 2.The assembly 62 is a non-limiting example of suitable configurations andintegration of the cutting laser subsystem 44, the ranging subsystem 46,the alignment guidance subsystem 48, the shared optics 50, and thepatient interface 52. Other configurations and integration of thecutting laser subsystem 44, the ranging subsystem 46, the alignmentguidance subsystem 48, the shared optics 50, and the patient interface52 may be possible and may be apparent to a person of skill in the art.

The assembly 62 is operable to project and scan optical beams into thepatient's eye 43. The cutting laser subsystem 44 includes an ultrafast(UF) laser 64 (e.g., a femtosecond laser). Using the assembly 62,optical beams can be scanned in the patient's eye 43 in threedimensions: X, Y, Z. For example, short-pulsed laser light generated bythe UF laser 64 can be focused into eye tissue to produce dielectricbreakdown to cause photodisruption around the focal point (the focalzone), thereby rupturing the tissue in the vicinity of the photo-inducedplasma. In the assembly 62, the wavelength of the laser light can varybetween 800 nm to 1200 nm and the pulse width of the laser light canvary from 10 fs to 10000 fs. The pulse repetition frequency can alsovary from 10 kHz to 500 kHz. Safety limits with regard to unintendeddamage to non-targeted tissue bound the upper limit with regard torepetition rate and pulse energy. Threshold energy, time to complete theprocedure, and stability can bound the lower limit for pulse energy andrepetition rate. The peak power of the focused spot in the eye 43 andspecifically within the crystalline lens and the lens capsule of the eyeis sufficient to produce optical breakdown and initiate aplasma-mediated ablation process. Near-infrared wavelengths for thelaser light are preferred because linear optical absorption andscattering in biological tissue is reduced for near-infraredwavelengths. As an example, the laser 64 can be a repetitively pulsed1031 nm device that produces pulses with less than 600 fs duration at arepetition rate of 120 kHz (+/−5%) and individual pulse energy in the 1to 20 micro joule range.

The cutting laser subsystem 44 is controlled by the control electronics54 and the user, via the control panel/GUI 56 and the user interfacedevices 58, to create a laser pulse beam 66. The control panel/GUI 56 isused to set system operating parameters, process user input, displaygathered information such as images of ocular structures, and displayrepresentations of incisions to be formed in the patient's eye 43.

The generated laser pulse beam 66 proceeds through a zoom assembly 68.The laser pulse beam 66 may vary from unit to unit, particularly whenthe UF laser 64 may be obtained from different laser manufacturers. Forexample, the beam diameter of the laser pulse beam 66 may vary from unitto unit (e.g., by +/−20%). The beam may also vary with regard to beamquality, beam divergence, beam spatial circularity, and astigmatism. Inmany embodiments, the zoom assembly 68 is adjustable such that the laserpulse beam 66 exiting the zoom assembly 68 has consistent beam diameterand divergence unit to unit.

After exiting the zoom assembly 68, the laser pulse beam 66 proceedsthrough an attenuator 70. The attenuator 70 is used to adjust thetransmission of the laser beam and thereby the energy level of the laserpulses in the laser pulse beam 66. The attenuator 70 is controlled viathe control electronics 54.

After exiting the attenuator 70, the laser pulse beam 66 proceedsthrough an aperture 72. The aperture 72 sets the outer useful diameterof the laser pulse beam 66. In turn the zoom determines the size of thebeam at the aperture location and therefore the amount of light that istransmitted. The amount of transmitted light is bounded both high andlow. The upper is bounded by the requirement to achieve the highestnumerical aperture achievable in the eye. High NA promotes low thresholdenergies and greater safety margin for untargeted tissue. The lower isbound by the requirement for high optical throughput. Too muchtransmission loss in the system shortens the lifetime of the system asthe laser output and system degrades over time. Additionally,consistency in the transmission through this aperture promotes stabilityin determining optimum settings (and sharing of) for each procedure.Typically to achieve optimal performance the transmission through thisaperture as set to be between 88% to 92%.

After exiting the aperture 72, the laser pulse beam 66 proceeds throughtwo output pickoffs 74. Each output pickoff 74 can include a partiallyreflecting mirror to divert a portion of each laser pulse to arespective output monitor 76. Two output pickoffs 74 (e.g., a primaryand a secondary) and respective primary and secondary output monitors 76are used to provide redundancy in case of malfunction of the primaryoutput monitor 76.

After exiting the output pickoffs 74, the laser pulse beam 66 proceedsthrough a system-controlled shutter 78. The system-controlled shutter 78ensures on/off control of the laser pulse beam 66 for procedural andsafety reasons. The two output pickoffs precede the shutter allowing formonitoring of the beam power, energy, and repetition rate as apre-requisite for opening the shutter.

After exiting the system-controlled shutter 78, the optical beamproceeds through an optics relay telescope 80. The optics relaytelescope 80 propagates the laser pulse beam 66 over a distance whileaccommodating positional and/or directional variability of the laserpulse beam 66, thereby providing increased tolerance for componentvariation. As an example, the optical relay can be a keplerian afocaltelescope that relays an image of the aperture position to a conjugateposition near to the XY galvo mirror positions. In this way, theposition of the beam at the XY galvo location is invariant to changes inthe beams angle at the aperture position. Similarly the shutter does nothave to precede the relay and may follow after or be included within therelay.

After exiting the optics relay telescope 80, the laser pulse beam 66 istransmitted to the shared optics 50, which propagates the laser pulsebeam 66 to the patient interface 52. The laser pulse beam 66 is incidentupon a beam combiner 82, which reflects the laser pulse beam 66 whiletransmitting optical beams from the ranging subsystem 46 and thealignment guidance subsystem: AIM 48.

Following the beam combiner 82, the laser pulse beam 66 continuesthrough a Z-telescope 84, which is operable to scan focus position ofthe laser pulse beam 66 in the patient's eye 43 along the Z axis. Forexample, the Z-telescope 84 can include a Galilean telescope with twolens groups (each lens group includes one or more lenses). One of thelens groups moves along the Z axis about the collimation position of theZ-telescope 84. In this way, the focus position of the spot in thepatient's eye 43 moves along the Z axis. In general, there is arelationship between the motion of lens group and the motion of thefocus point. For example, the Z-telescope can have an approximate 2×beam expansion ratio and close to a 1:1 relationship of the movement ofthe lens group to the movement of the focus point. The exactrelationship between the motion of the lens and the motion of the focusin the z axis of the eye coordinate system does not have to be a fixedlinear relationship. The motion can be nonlinear and directed via amodel or a calibration from measurement or a combination of both.Alternatively, the other lens group can be moved along the Z axis toadjust the position of the focus point along the Z axis. The Z-telescope84 functions as z-scan device for scanning the focus point of thelaser-pulse beam 66 in the patient's eye 43. The Z-telescope 84 can becontrolled automatically and dynamically by the control electronics 54and selected to be independent or to interplay with the X and Y scandevices described next.

After passing through the Z-telescope 84, the laser pulse beam 66 isincident upon an X-scan device 86, which is operable to scan the laserpulse beam 66 in the X direction, which is dominantly transverse to theZ axis and transverse to the direction of propagation of the laser pulsebeam 66. The X-scan device 86 is controlled by the control electronics54, and can include suitable components, such as a motor, galvanometer,or any other well-known optic moving device. The relationship of themotion of the beam as a function of the motion of the X actuator doesnot have to be fixed or linear. Modeling or calibrated measurement ofthe relationship or a combination of both can be determined and used todirect the location of the beam.

After being directed by the X-scan device 86, the laser pulse beam 66 isincident upon a Y-scan device 88, which is operable to scan the laserpulse beam 66 in the Y direction, which is dominantly transverse to theX and Z axes. The Y-scan device 88 is controlled by the controlelectronics 54, and can include suitable components, such as a motor,galvanometer, or any other well-known optic moving device. Therelationship of the motion of the beam as a function of the motion ofthe Y actuator does not have to be fixed or linear. Modeling orcalibrated measurement of the relationship or a combination of both canbe determined and used to direct the location of the beam.Alternatively, the functionality of the X-Scan device 86 and the Y-Scandevice 88 can be provided by an XY-scan device configured to scan thelaser pulse beam 66 in two dimensions transverse to the Z axis and thepropagation direction of the laser pulse beam 66. The X-scan and Y-scandevices 86, 88 change the resulting direction of the laser pulse beam66, causing lateral displacements of UF focus point located in thepatient's eye 43.

After being directed by the Y-scan device 88, the laser pulse beam 66passes through a beam combiner 90. The beam combiner 90 is configured totransmit the laser pulse beam 66 while reflecting optical beams to andfrom a video subsystem 92 of the alignment guidance subsystem 48.

After passing through the beam combiner 90, the laser pulse beam 66passes through an objective lens assembly 94. The objective lensassembly 94 can include one or more lenses. In many embodiments, theobjective lens assembly 94 includes multiple lenses. The complexity ofthe objective lens assembly 94 may be driven by the scan field size, thefocused spot size, the degree of telecentricity, the available workingdistance on both the proximal and distal sides of objective lensassembly 94, as well as the amount of aberration control.

After passing through the objective lens assembly 94, the laser pulsebeam 66 passes through the patient interface 52. As described above, inmany embodiments, the patient interface 52 includes a patient interfacelens 96 having a posterior surface that is displaced vertically from theanterior surface of the patient's cornea and a region of a suitableliquid (e.g., a sterile buffered saline solution (BSS) such as Alcon BSS(Alcon Part Number 351-55005-1) or equivalent) is disposed between andin contact with the posterior surface of the patient interface lens 96and the patient's cornea and forms part of an optical transmission pathbetween the shared optics 50 and the patient's eye 43.

The shared optics 50 under the control of the control electronics 54 canautomatically generate aiming, ranging, and treatment scan patterns.Such patterns can be comprised of a single spot of light, multiple spotsof light, a continuous pattern of light, multiple continuous patterns oflight, and/or any combination of these. In addition, the aiming pattern(using the aim beam 108 described below) need not be identical to thetreatment pattern (using the laser pulse beam 66), but can optionally beused to designate the boundaries of the treatment pattern to provideverification that the laser pulse beam 66 will be delivered only withinthe desired target area for patient safety. This can be done, forexample, by having the aiming pattern provide an outline of the intendedtreatment pattern. This way the spatial extent of the treatment patterncan be made known to the user, if not the exact locations of theindividual spots themselves, and the scanning thus optimized for speed,efficiency, and/or accuracy. The aiming pattern can also be made to beperceived as blinking in order to further enhance its visibility to theuser. Likewise, the ranging beam 102 need not be identical to thetreatment beam or pattern. The ranging beam needs only to be sufficientenough to identify targeted surfaces. These surfaces can include thecornea and the anterior and posterior surfaces of the lens and may beconsidered spheres with a single radius of curvature. Also the opticsshared by the alignment guidance: video subsystem does not have to beidentical to those shared by the treatment beam. The positioning andcharacter of the laser pulse beam 66 and/or the scan pattern the laserpulse beam 66 forms on the eye 43 may be further controlled by use of aninput device such as a joystick, or any other appropriate user inputdevice (e.g., control panel/GUI 56) to position the patient and/or theoptical system.

The control electronics 54 can be configured to target the targetedstructures in the eye 43 and ensure that the laser pulse beam 66 will befocused where appropriate and not unintentionally damage non-targetedtissue. Imaging modalities and techniques described herein, such asthose mentioned above, or ultrasound may be used to determine thelocation and measure the thickness of the lens and lens capsule toprovide greater precision to the laser focusing methods, including 2Dand 3D patterning. Laser focusing may also be accomplished by using oneor more methods including direct observation of an aiming beam, or otherknown ophthalmic or medical imaging modalities, such as those mentionedabove, and/or combinations thereof. Additionally the ranging subsystemsuch as an OCT can be used to detect features or aspects involved withthe patient interface. Features can include fiducials places on thedocking structures and optical structures of the disposable lens such asthe location of the anterior and posterior surfaces.

In the embodiment of FIG. 3A, the ranging subsystem 46 includes an OCTimaging device. Additionally or alternatively, imaging modalities otherthan OCT imaging can be used. An OCT scan of the eye can be used tomeasure the spatial disposition (e.g., three dimensional coordinatessuch as X, Y, and Z of points on boundaries) of structures of interestin the patient's eye 43. Such structure of interest can include, forexample, the anterior surface of the cornea, the posterior surface ofthe cornea, the anterior portion of the lens capsule, the posteriorportion of the lens capsule, the anterior surface of the crystallinelens, the posterior surface of the crystalline lens, the iris, thepupil, and/or the limbus. The spatial disposition of the structures ofinterest and/or of suitable matching geometric modeling such as surfacesand curves can be generated and/or used by the control electronics 54 toprogram and control the subsequent laser-assisted surgical procedure.The spatial disposition of the structures of interest and/or of suitablematching geometric modeling can also be used to determine a wide varietyof parameters related to the procedure such as, for example, the upperand lower axial limits of the focal planes used for cutting the lenscapsule and segmentation of the lens cortex and nucleus, and thethickness of the lens capsule among others.

The ranging subsystem 46 in FIG. 3A includes an OCT light source anddetection device 98. The OCT light source and detection device 98includes a light source that generates and emits light with a suitablebroad spectrum. For example, in many embodiments, the OCT light sourceand detection device 98 generates and emits light with a broad spectrumfrom 810 nm to 850 nm wavelength. The generated and emitted light iscoupled to the device 98 by a single mode fiber optic connection.

The light emitted from the OCT light source and detection device 98 ispassed through a beam combiner 100, which divides the light into asample portion 102 and a reference portion 104. A significant portion ofthe sample portion 102 is transmitted through the shared optics 50. Arelative small portion of the sample portion is reflected from thepatient interface 52 and/or the patient's eye 43 and travels backthrough the shared optics 50, back through the beam combiner 100 andinto the OCT light source and detection device 98. The reference portion104 is transmitted along a reference path 106 having an adjustable pathlength. The reference path 106 is configured to receive the referenceportion 104 from the beam combiner 100, propagate the reference portion104 over an adjustable path length, and then return the referenceportion 106 back to the beam combiner 100, which then directs thereturned reference portion 104 back to the OCT light source anddetection device 98. The OCT light source and detection device 98 thendirects the returning small portion of the sample portion 102 and thereturning reference portion 104 into a detection assembly, which employsa time domain detection technique, a frequency detection technique, or asingle point detection technique. For example, a frequency-domaintechnique can be used with an OCT wavelength of 830 nm and bandwidth of10 nm.

Once combined with the UF laser pulse beam 66 subsequent to the beamcombiner 82, the OCT sample portion beam 102 follows a shared path withthe UF laser pulse beam 66 through the shared optics 50 and the patientinterface 52. In this way, the OCT sample portion beam 102 is generallyindicative of the location of the UF laser pulse beam 66. Similar to theUF laser beam, the OCT sample portion beam 102 passes through theZ-telescope 84, is redirected by the X-scan device 86 and by the Y-scandevice 88, passes through the objective lens assembly 94 and the patientinterface 52, and on into the eye 43. Reflections and scatter off ofstructures within the eye provide return beams that retrace back throughthe patient interface 52, back through the shared optics 50, backthrough the beam combiner 100, and back into the OCT light source anddetection device 98. The returning back reflections of the sampleportion 102 are combined with the returning reference portion 104 anddirected into the detector portion of the OCT light source and detectiondevice 98, which generates OCT signals in response to the combinedreturning beams. The generated OCT signals that are in turn interpretedby the control electronics to determine the spatial disposition of thestructures of interest in the patient's eye 43. The generated OCTsignals can also be interpreted by the control electronics to measurethe position and orientation of the patient interface 52, as well as todetermine whether there is liquid disposed between the posterior surfaceof the patient interface lens 96 and the patient's eye 43.

The OCT light source and detection device 98 works on the principle ofmeasuring differences in optical path length between the reference path106 and the sample path. Therefore, different settings of theZ-telescope 84 to change the focus of the UF laser beam do not impactthe length of the sample path for a axially stationary surface in theeye of patient interface volume because the optical path length does notchange as a function of different settings of the Z-telescope 84. Theranging subsystem 46 has an inherent Z range that is related to lightsource and the detection scheme, and in the case of frequency domaindetection the Z range is specifically related to the spectrometer, thewavelength, the bandwidth, and the length of the reference path 106. Inthe case of ranging subsystem 46 used in FIG. 3A, the Z range isapproximately 4-5 mm in an aqueous environment. Extending this range toat least 20-25 mm involves the adjustment of the path length of thereference path 106 via a stage ZED within ranging subsystem 46. Passingthe OCT sample portion beam 102 through the Z-telescope 84, while notimpacting the sample path length, allows for optimization of the OCTsignal strength. This is accomplished by focusing the OCT sample portionbeam 102 onto the targeted structure. The focused beam both increasesthe return reflected or scattered signal that can be transmitted throughthe single mode fiber and increases the spatial resolution due to thereduced extent of the focused beam. The changing of the focus of thesample OCT beam can be accomplished independently of changing the pathlength of the reference path 106.

Because of the fundamental differences in how the sample portion 102(e.g., 810 nm to 850 nm wavelengths) and the UF laser pulse beam 66(e.g., 1020 nm to 1050 nm wavelengths) propagate through the sharedoptics 50 and the patient interface 52 due to influences such asimmersion index, refraction, and aberration, both chromatic andmonochromatic, care must be taken in analyzing the OCT signal withrespect to the UF laser pulse beam 66 focal location. A calibration orregistration procedure as a function of X, Y, and Z can be conducted inorder to match the OCT signal information to the UF laser pulse beamfocus location and also to the relative to absolute dimensionalquantities.

There are many suitable possibilities for the configuration of the OCTinterferometer. For example, alternative suitable configurations includetime and frequency domain approaches, single and dual beam methods,swept source, etc., are described in U.S. Pat. Nos. 5,748,898;5,748,352; 5,459,570; 6,111,645; and 6,053,613.

The system 2 can be set to locate the anterior and posterior surfaces ofthe lens capsule and cornea and ensure that the UF laser pulse beam 66will be focused on the lens capsule and cornea at all points of thedesired opening. Imaging modalities and techniques described herein,such as for example, Optical Coherence Tomography (OCT), and such asPurkinje imaging, Scheimpflug imaging, confocal or nonlinear opticalmicroscopy, fluorescence imaging, ultrasound, structured light, stereoimaging, or other known ophthalmic or medical imaging modalities and/orcombinations thereof may be used to determine the shape, geometry,perimeter, boundaries, and/or 3-dimensional location of the lens andlens capsule and cornea to provide greater precision to the laserfocusing methods, including 2D and 3D patterning. Laser focusing mayalso be accomplished using one or more methods including directobservation of an aiming beam, or other known ophthalmic or medicalimaging modalities and combinations thereof, such as but not limited tothose defined above.

Optical imaging of the cornea, anterior chamber and lens can beperformed using the same laser and/or the same scanner used to producethe patterns for cutting. Optical imaging can be used to provideinformation about the axial location and shape (and even thickness) ofthe anterior and posterior lens capsule, the boundaries of the cataractnucleus, as well as the depth of the anterior chamber and features ofthe cornea. This information may then be loaded into the laser 3-Dscanning system or used to generate a three dimensionalmodel/representation/image of the cornea, anterior chamber, and lens ofthe eye, and used to define the cutting patterns used in the surgicalprocedure.

Observation of an aim beam can also be used to assist in positioning thefocus point of the UF laser pulse beam 66. Additionally, an aim beamvisible to the unaided eye in lieu of the infrared OCT sample portionbeam 102 and the UF laser pulse beam 66 can be helpful with alignmentprovided the aim beam accurately represents the infrared beamparameters. The alignment guidance subsystem 48 is included in theassembly 62 shown in FIG. 3A. An aim beam 108 is generated by an aimbeam light source 110, such as a laser diode in the 630-650 nm range.

Once the aim beam light source 110 generates the aim beam 108, the aimbeam 108 is transmitted along an aim path 112 to the shared optics 50,where it is redirected by a beam combiner 114. After being redirected bythe beam combiner 114, the aim beam 108 follows a shared path with theUF laser pulse beam 66 through the shared optics 50 and the patientinterface 52. In this way, the aim beam 108 is indicative of thelocation of the UF laser pulse beam 66. The aim beam 108 passes throughthe Z-telescope 84, is redirected by the X-scan device 86 and by theY-scan device 88, passes through the beam combiner 90, passes throughthe objective lens assembly 94 and the patient interface 52, and on intothe patient's eye 43.

The video subsystem 92 is operable to obtain images of the patientinterface and the patient's eye. The video subsystem 92 includes acamera 116, an illumination light source 118, and a beam combiner 120.The video subsystem 92 gathers images that can be used by the controlelectronics 54 for providing pattern centering about or within apredefined structure. The illumination light source 118 can be generallybroadband and incoherent. For example, the light source 118 can includemultiple LEDs. The wavelength of the illumination light source 118 ispreferably in the range of 700 nm to 750 nm, but can be anything that isaccommodated by the beam combiner 90, which combines the light from theillumination light source 118 with the beam path for the UF laser pulsebeam 66, the OCT sample beam 102, and the aim beam 108 (beam combiner 90reflects the video wavelengths while transmitting the OCT and UFwavelengths). The beam combiner 90 may partially transmit the aim beam108 wavelength so that the aim beam 108 can be visible to the camera116. An optional polarization element can be disposed in front of theillumination light source 118 and used to optimize signal. The optionalpolarization element can be, for example, a linear polarizer, a quarterwave plate, a half-wave plate or any combination. An additional optionalanalyzer can be placed in front of the camera. The polarizer analyzercombination can be crossed linear polarizers thereby eliminatingspecular reflections from unwanted surfaces such as the objective lenssurfaces while allowing passage of scattered light from targetedsurfaces such as the intended structures of the eye. The illuminationmay also be in a dark-filed configuration such that the illuminationsources are directed to the independent surfaces outside the capturenumerical aperture of the image portion of the video system.Alternatively the illumination may also be in a bright fieldconfiguration. In both the dark and bright field configurations, theillumination light source can be used as a fixation beam for thepatient. The illumination may also be used to illuminate the patient'spupil to enhance the pupil iris boundary to facilitate iris detectionand eye tracking. A false color image generated by the near infraredwavelength or a bandwidth thereof may be acceptable.

The illumination light from the illumination light source 118 istransmitted through the beam combiner 120 to the beam combiner 90. Fromthe beam combiner 90, the illumination light is directed towards thepatient's eye 43 through the objective lens assembly 94 and through thepatient interface 94. The illumination light reflected and scattered offof various structures of the eye 43 and patient interface travel backthrough the patient interface 94, back through the objective lensassembly 94, and back to the beam combiner 90. At the beam combiner 90,the returning light is directed back to the beam combiner 120 where thereturning light is redirected toward the camera 116. The beam combinercan be a cube, plate or pellicle element. It may also be in the form ofa spider mirror whereby the illumination transmits past the outer extentof the mirror while the image path reflects off the inner reflectingsurface of the mirror. Alternatively, the beam combiner could be in theform of a scraper mirror where the illumination is transmitted through ahole while the image path reflects off of the mirrors reflecting surfacethat lies outside the hole. The camera 116 can be a suitable imagingdevice, for example but not limited to, any silicon based detector arrayof the appropriately sized format. A video lens forms an image onto thecamera's detector array while optical elements provide polarizationcontrol and wavelength filtering respectively. An aperture or irisprovides control of imaging NA and therefore depth of focus and depth offield and resolution. A small aperture provides the advantage of largedepth of field that aids in the patient docking procedure.Alternatively, the illumination and camera paths can be switched.Furthermore, the aim light source 110 can be made to emit infrared lightthat would not be directly visible, but could be captured and displayedusing the video subsystem 92.

FIG. 3B shows a mapped treatment region of the eye comprising thecornea, the posterior capsule, and the limbus. The treatment region canbe mapped with computer modeling, for example ray tracing and phasedbased optical modeling to incorporate factors such as laser beamquality, pulse width, system transmission, numerical aperture,polarization, aberration correction, and alignment. The treatment volumeis shown extending along the Z-axis from the posterior surface of theoptically transmissive structure of the patient interface a distance ofover 15 mm, such that the treatment volume includes the cornea, and thelens in which the treatment volume of the lens includes the anteriorcapsule, the posterior capsule, the nucleus and the cortex. Thetreatment volume extends laterally from the center of the cornea tobeyond the limbus. The lateral dimensions of the volume are defined by aY contour anterior to the limbus and by an X contour posterior to thelimbus. The treatment volume shown can be determined by a person ofordinary skill in the art based on the teachings described herein. Thelateral positions of predicted optical breakdown for ZL fixed to 30 mmand ZL fixed to 20 mm are shown. These surfaces that extend transverseto the axis 99 along the Z-dimension correspond to locations of opticalscanning of the X and Y galvos to provide optical breakdown at laterallocations away from the axis 99. The curved non-planar shape of the scanpath of optical breakdown for ZL-30 mm and ZL-20 mm can be correctedwith the mapping and look up tables as described herein. The curvedshape of the focus can be referred to as a warping of the opticalbreakdown depth and the look up tables can be warped oppositely orotherwise adjusted so as to compensate for the warping of the treatmentdepth, for example. Additionally, the warping inherent in the predictionfrom the model can be incorporated in the generic look-up table and anyfurther error from this predicted form as indicated by measurement andapplication of a correction factor to offset this error may also becalled a warping of the look up table.

The treatment region is shown for setting the laser beam energy aboutfour times the threshold amount for optical breakdown empiricallydetermined for a beam near the limbus of the system. The increasedenergy or margin above ensures that the beam system will be able totreat given variability in contributing factors. Theses contributingfactors may include degradation over lifetime of the laser with regardto energy, beam quality, transmission of the system, and alignment.

The placement of the posterior surface of the optically transmissivestructure of the patient interface away from the surface of the corneacan provide the extended treatment range as shown, and in manyembodiments the optically transmissive structure comprises the lens. Inalternative embodiments, the posterior surface of the opticallytransmissive structure can be placed on the cornea, for example, and themapping and look up tables as described herein can be used to providethe patient treatment with improved accuracy.

The optically transmissive structure of the patient interface maycomprise one or more of many known optically transmissive materials usedto manufactures lenses, plates and wedges, for example one or more ofglass, BK-7, plastic, acrylic, silica or fused silica for example.

The computer mapping of the treatment volume may optionally be adjustedwith mapping based on measurements of a constructed system as describedherein.

FIG. 3C shows mapped changes in beam focus for locations of the mappedtreatment region. The locations of optical breakdown can be mapped at aplurality of depths and lateral locations so as to map the location ofoptical breakdown over the treatment volume. The laser beam spotirradiance can be determined with computer modeling software, forexample. The location of optical breakdown can be determined based onthe laser beam spot irradiance pattern, such that the location ofoptical breakdown along the laser beam path can be determined. Theoptical breakdown for a given set of laser parameters such as beamquality and pulse width can occur at a combination of one or more ofpeak irradiance, spot shape, or polarization direction, for example. Themapped beam shape can be at planes of a treatment volume, for example.The mapped focus can be determined with commercially available opticalmodeling software based on the teachings described herein. The mappedchanges in beam focus may comprise a mapped focus at a depth of 8 mm onthe axis of the coordinate reference system, for example. Similarmapping can be performed at additional depths as described herein. Thefocused beam profile can be determined for the nominal location and +50um and −50 um, so as to evaluate the irradiance pattern to determine thelocation of optical breakdown. The focused beam profile can bedetermined at several locations along the plane away from the axis. Forexample, the beam profile can be determined at locations along a radiusof the treatment volume, such as at the 0, 45 and 90 degree locationsalong a 7 mm circle, for example.

In many embodiments, the laser beam output energy comprises a valuesubstantially above the amount required near the center of the treatmentvolume, for example four times the amount required at the center, so asto provide optical breakdown near the edges of the treatment volume, andthe location of optical breakdown can be determined based on the beamspot irradiance profile and the output energy of the laser. This mappingcan be performed initially in software, and may optionally be furtherrefined based on mapping measurements of a constructed system asdescribed herein.

FIG. 4A shows correspondence among movable and sensor components of thelaser delivery system 2. The movable components may comprise one or morecomponents of the laser delivery system 2 as described herein. Themovable components of the laser delivery system may comprise the zoomlens capable of moving distance ZL, the X galvo mirror 96 capable ofmoving an angular amount Xm, and the Y galvo mirror 88 capable of movingan angular amount Ym. The movable components of the OCT system maycomprise the movable OCT reference arm configured to move the referencepath 106 a distance ZED. The sensor components of the laser system maycomprise the video camera having X and Y pixels, Pix X and Pix Y,respectively, and sensor components of the OCT system such as thespectral domain detection as described herein. The patient support whichmay comprise a bed is movable in three dimensions so as to align the eye43 of the patient P with laser system 2 and axis 99 of the system. Thepatient interface assembly comprises an optically transmissive structurewhich may comprise an interface lens 96, for example, configured to bealigned with system 2 and an axis of eye 43. The patient interface lenscan be placed on the patient eye 43 for surgery, and the opticallytransmissive structure can be placed at a distance 162 from theobjective lens 94. In many embodiments, the optically transmissivestructure comprises lens 96 placed a contact lens optical distance 162(hereinafter “CLopt”). The optically transmissive structure comprises athickness 164, and the thickness 164 may comprise a thickness of thecontact lens 96, for example. Although the optically transmissivestructure comprising contact lens 96 may contact the eye 2, in manyembodiments the contact lens 168 is separated from the cornea with gap168 extending between the lens and the vertex of the cornea, such thatthe posterior surface of the contact lens 168 contacts a solutioncomprising saline or a viscoelastic solution, for example.

FIG. 4B shows mapping of coordinate references from an eye spacecoordinate reference system 150 to a machine coordinate reference system151 so as to coordinate the machine components with the physicallocations of the eye. The laser system 2 can map physical coordinates ofthe eye 43 to machine coordinates of the components as described herein.The eye space coordinate reference system 150 comprises a first Xdimension 152, for example an X axis, a second Y dimension 154, forexample a Y axis, and a third Z dimension 156, for example a Z axis, andthe coordinate reference system of the eye may comprise one or more ofmany known coordinate systems such as polar, cylindrical or Cartesian,for example.

In many embodiments, the eye coordinate reference system corresponds tophysical dimensions of the eye, which can be determined based on thetomography, video, and other measurements of the eye corrected with therefraction of the eye and the index of refraction of the eye asdescribed herein, for example. For a targeted physical location of theeye having eye coordinate references based on the coordinate referencesystem 150, the processor can determine the machine coordinates of themachine coordinate reference system in one or more of many ways asdescribed herein.

In many embodiments the reference system 150 comprises a right handedtriple with the X axis oriented in a nasal temporal direction on thepatient, the Y axis oriented superiorly on the patient and the Z axisoriented posteriorly on the patient. In many embodiments, thecorresponding machine coordinate reference system 151 comprises a firstX′ dimension 153, a second Y′ dimension 155, and a third Z′ dimension157 generally corresponding to machine actuators, and the coordinatereference system of the machine may comprise one or more of many knowncoordinate systems such as polar, cylindrical or Cartesian, andcombinations thereof, for example.

The machine coordinate reference 151 may correspond to locations of oneor more components of system 2. The machine coordinate reference system151 may comprise a plurality of machine coordinate reference systems.The plurality of machine coordinate reference systems may comprise acoordinate reference system for each subsystem, for example. Forexample, dimension 157 may correspond to movement of the z-telescopelens capable of moving distance ZL. The dimension 153 may correspond tomovement of the X galvo mirror 86 capable of moving an angular amountXm, and the dimension 153 may correspond to movement of the Y galvomirror 88 capable of moving an angular amount Ym. Alternatively or incombination, the dimension 157 may correspond to movable OCT referencearm configured to move the reference path 106 a distance ZED, along withdimension 157 corresponding to a movement of the z-telescope for the OCTbeam, and the dimension 153 and the dimension 155 may correspond tomovement of the X galvo mirror 86 and the Y galvo mirror 88,respectively, for the OCT beam. The dimension 151 may correspond to Xpixels of the video camera and dimension 153 may correspond to Y pixelsof the video camera. The axes of the machine coordinate reference systemmay be combined in one or more of many ways, for example the OCTreference arm movement of the reference path 106 the distance ZED can becombined with movement of the z-telescope lens capable of moving thedistance ZL, for example. In many embodiments, the locations of thecomponents of the laser system 2 are combined when in order to map theplurality of machine coordinate reference systems to the coordinatereference system 150 of eye 43.

In many embodiments, the eye coordinate reference system is mapped froman optical path length coordinate system to physical coordinates of theeye based on the index of refraction of the tissues of the eye. Anexample is the OCT ranging system where measurements are based onoptical thicknesses. The physical distance can be obtained by dividingthe optical path length by the index of refraction of the materialthrough which the light beam passes. Preferable the group refractiveindex is used and takes into account the group velocity of the lightwith a center wavelength and bandwidth and dispersion characteristics ofthe beam train. When the beam has passed through more than one material,the physical distance can be determined based on the optical path lengththrough each material, for example. The tissue structures of the eye andcorresponding index of refraction can be identified and the physicallocations of the tissue structures along the optical path determinedbased on the optical path length and the indices of refraction. When theoptical path length extends along more than one tissue, the optical pathlength for each tissue can be determined and divided by thecorresponding index of refraction so as to determine the physicaldistance through each tissue, and the distances along the optical pathcan be combined, for example with addition, so as to determine thephysical location of a tissue structure along the optical path length.Additionally, optical train characteristics may be taken into account.As the OCT beam is scanned in the X and Y directions and departure fromthe telecentric condition occurs due to the axial location of the galvomirrors, a distortion of the optical path length is realized. This iscommonly known as fan error and can be corrected for either throughmodeling or measurement.

As one or more optical components and light sources as described hereinmay have different path lengths, wavelengths, and spectral bandwidths,in many embodiments the group index of refraction used depends on thematerial and the wavelength and spectral bandwidth of the light beam. Inmany embodiments, the index of refraction along the optical path maychange with material. For example, the saline solution may comprise afirst index of refraction, the cornea may comprise a second index ofrefraction, the anterior chamber of the eye may comprise a third indexof refraction, and the eye may comprise gradient index lens having aplurality of indices of refraction. While optical path length throughthese materials is governed by the group index of refraction, refractionor bending of the beam is governed by the phase index of the material.Both the phase and group index can be taken into account to accuratelydetermine the X, Y, and Z location of a structure. While the index ofrefraction of tissue such as eye 43 can vary with wavelength asdescribed herein, approximate values include: aqueous humor 1.33; cornea1.38; vitreous humor 1.34; and lens 1.36 to 1.41, in which the index ofthe lens can differ for the capsule, the cortex and the nucleus, forexample. The phase index of refraction of water and saline can be about1.325 for the ultrafast laser at 1030 nm and about 1.328 for the OCTsystem at 830 nm. The group refractive index of 1.339 differs on theorder of 1% for the OCT beam wavelength and spectral bandwidth. A personof ordinary skill in the art can determine the indices of refraction andgroup indices of refraction of the tissues of the eye for thewavelengths of the measurement and treatment systems as describedherein. The index of refraction of the other components of the systemcan be readily determined by a person of ordinary skill in the art basedon the teachings described herein.

FIG. 4C shows a feedback loop to adjust look up table calibrationmapping from a generalized system having nominal values to a specificindividual constructed system based on measurements of the individualconstructed system. The system 2 may comprise a generalized system basedon optical schematics and components. The generalized system maycomprise an optical design as described herein, which can be associatedwith one or more of product code and scripts, merit functions, opticalspecifications, a nominal system design of the components and locations,and tolerances associated with the nominal system design components andlocations. In the execution of the system design, the optical design isoutput as optical components and specifications, which can be used toconfigured optical assemblies. The optical assemblies and components arealigned. The generalized system design can be further improved withfeedback. The feedback of the generalized system design may comprisecalibration tests and optical modeling that are used to further improveand modify the optical design. For example, a system can be constructedbased on the nominal design and information from the nominal design fedback to the optical design based on calibration and testing, such astolerances of components and range of treatment. The nominal design ofthe general system can be used to generate a generalized look up tablebased on the nominal design. The nominal LUTS and SW factors can be usedto produce a final production system, and the final production systemcan undergo final test procedures.

In accordance with many embodiments, an enhanced customized system 2 canbe constructed based on the customized feedback path so as to provide acustomized system. While the customized system can be provided in manyways, in many embodiments a production SW tool is used to customize theparameters of individual system so as to provide an enhanced model ofsystem behavior and improved accuracy of the mapping as describedherein. The production SW tool can be used to determine customized lookup tables of the system 2, and to provide enhanced calibration of system2. The nominal values output from the generalized nominal system atdesign execution stage can be output to the LUTs and software factors,which can be combined with the customized feedback to provide anenhanced product. The modification to the LUTs to transform the system 2from the generalized nominal system to the constructed system withcustomized parameters can be provided with calibration of theconstructed system as described herein.

FIG. 5 shows a method 300 of calibration for laser system 2. The lasersystem 2 can be calibrated such that positions and angles of thecomponents and actuators of the laser system are mapped onto locationsof the eye 43. The method 300 can be performed on each build of a lasersystem, and can be used to improve the accuracy of a specific lasersystem. In many embodiments, the system specific calibration can be usedto improve the correspondence between the treatment locations of the eyeand the machine coordinates as described herein. Although reference ismade to Z-axis alignment, similar methods and apparatus can be used toimprove the accuracy of the system along other dimensions, such as X andY dimensions, for example. Method 300 can be combined with opticalbreakdown threshold energy mapping as described herein, for example.Method 300 can be particularly well suited for calibration of the systemwith a first lens of the patient interface, in order to use a secondlens of the patient interface to treat the patient accurately. Aplurality of many additional patient interface lenses can be used basedon the alignment with the first lens, for example. The methods andapparatus can be used to determine specific laser treatment parametersfor a specific patient interface lens placed in the system for aspecific eye, for example.

At a step 305, values of Xm, Ym, and ZL (where Xm corresponds to theangle of the X galvo mirror, Ym corresponds to the angle of the Y galvomirror, and ZL corresponds to the movement of the lens in thez-telescope) are determined within a treatment volume for the ultrafastfemto second laser so as to provide corresponding X, Y and Z locationsof the eye. The locations can be determined based on mapping and look uptables (herein after “LUT”), for example. The mapped locations candepend on the location and shape of the optically transmissive structuresuch as lens 168, the distance 162, distance 164, and the distance 168,for example. The mapping locations may also depend on the lasercharacteristics such as beam quality, pulse width, polarization, andenergy per pulse. The mapping locations may also depend on thecharacteristics of the optical system such as axial magnification,lateral magnification, numerical aperture, degree of telecentricity,aberration, and alignment.

At a step 310, values of Xm, Ym, ZL and ZED (where Xm, Ym, and ZL aredefined as before and ZED corresponds to the position of the OCTreference path length stage) are determined within a measurement volumefor the tomography system (such as the OCT system) so as to providecorresponding X, Y and Z locations of the eye or patient interface. Thelocations can be determined based on mapping and look up tables, forexample. The tomography system may comprise one or more of an OCTsystem, a confocal system, or a Scheimpflug system, an ultrasoundsystem, a high frequency ultrasound system, for example. The mappedlocations can depend on the location and shape of the opticallytransmissive structure such as lens 168, the distance 162, distance 164,and the distance 168, for example. The mapping locations may also dependon the light source characteristics such as wavelength, spectralbandwidth, and polarization. The mapping locations may also depend onthe characteristics of the optical system such as axial magnification,lateral magnification, numerical aperture, degree of telecentricity,aberration, and alignment.

At a step 315, values pixel X and pixel Y are determined within ameasurement volume for the video system so as to provide correspondingX, Y, and Z locations of the eye or patient interface. The locations canbe determined based on mapping and look up tables, for example. Thevideo is primarily a two-dimensional mapping of Xm, Ym to X, Y. Becauseof the large depth of field of the imaging path and the telecentricform, the Z location remains unchanged for the range of Z for which theimage is in focus. Accurate Z location can be determined using the OCTranging system or a priori knowledge. The mapped locations can depend onthe location and shape of the optically transmissive structure such aslens 168, the distance 162, distance 164, and the distance 168, forexample. The mapping locations may depend on the characteristics of theoptical system such as axial magnification, lateral magnification,numerical aperture, degree of telecentricity, aberration, and alignment.

At a step 320, a generic look up table is determined for the positionparameters of the system in response to targeted locations of the eye.The generic look up table can combine the above mapped values of Xm, Ym,ZL, & ZED based on one or more of distance 162, distance 164, distance168, dimension 152, dimension 154 or dimension 156, and combinationsthereof for example. The generic look up table can be constructed basedon ray tracing or other optically based analysis such as diffraction orwave based or gaussian beam propagation of the nominal opticalcomponents of the system and the movable components of the system toinclude the X galvo, the Y galvo, the Z-telescope, the attenuator, andthe chair, for example. The generic values of the look up table can mapeach eye coordinate location to a specific location or angle of each ofthe values of Xm, Ym, ZL, & ZED and other machine controllabledimensions, for each of the UF laser, the OCT system and the videosystem and aim alignment, for example. Although a look up table isdescribed, the mapping can be performed in one or more of many ways.

At a step 325, system specific corrections to the generic values aredetermined. The system specific look up table can be customized to themanufactured configuration of the system, and is capable ofaccommodating variation of the mapped components. The variation mayoccur with parts manufactured within specification but slightlydifferent from the generic or nominal system. For example, the opticalpower, placement and dimensions of the manufactured components maydiffer slightly from the generic system. The system specific LUT can begenerated based on the teachings described herein.

At a step 330, a system specific look up table (or tables) is determinedbased on the system specific corrections. The system specific look uptable can be combined with the generic look up table in many ways, forexample with corrections or adjustments comprising subtractions oradditions and scalings to the generic look up table.

At a step 335, the system specific look up table is used to generate alaser treatment of the eye so as to form laser generated incisions ofthe eye. The system specific look up table can be combined with atreatment table comprising a plurality of eye coordinate references, soas to provide specific instructions to components of the laser systemfor each location of the eye treatment given variations in knowndependencies such as from patient interface variations. The systemspecific look up table can be used to generate values of UF Xm, UF Ym,and UF ZL in order to control the positions of the correspondingcomponents.

At a step 340, At a step 335, the system specific look up table is usedto generate tomography values, such as values of OCT Xm, OCT Ym, OCT ZLand ZED values, so as to control Galvo Xm, Galvo Ym, Galvo Zm, and theOCT reference path length in order to image the eye and patientinterface given variations in known dependencies such as from patientinterface variations. The system specific look up table can be used togenerate values of OCT Xm, OCT Ym, OCT ZL in order to control thepositions of the corresponding components and ensure that the physicallocations of the eye structures and patient interface are accuratelymapped.

At a step 345, the system specific look up table is used to generate thePixel X and Pixel Y values corresponding to the given X, Y, Z, and CLthickness and displacement values used to form an image of the eye andpatient interface on the camera sensor array, and so as to accuratelymap the eye structures to three dimensional space in accordance with eyecoordinate reference system 150.

Although the above steps show method 300 of calibrating in accordancewith embodiments, a person of ordinary skill in the art will recognizemany variations based on the teaching described herein. The steps may becompleted in a different order. Steps may be added or deleted. Some ofthe steps may comprise sub-steps. Many of the steps may be repeated asoften as if beneficial to the treatment.

One or more of the steps of the method 300 may be performed with thecircuitry as described herein, for example one or more of the processoror logic circuitry such as the programmable array logic for fieldprogrammable gate array. The circuitry may be programmed to provide oneor more of the steps of method 300, and the program may comprise programinstructions stored on a computer readable memory or programmed steps ofthe logic circuitry such as the programmable array logic or the fieldprogrammable gate array, for example.

FIG. 6A shows an eye coordinate reference system 150 referenced to alower surface of an optically transmissive structure as part of apatient interface. The eye coordinate reference system can be mapped tothe machine coordinate reference system 151 as described herein.

The optically transmissive structure may comprise a flat plate, or alens having one or more curved surfaces. In many embodiments, theoptically transmissive structure comprises lens 96. The objective lens94 may comprise a plurality of achromatic infrared doubles, for examplethree achromatic infrared doublets.

The reference location 180 may comprise the origin of the coordinatesystem 150, and can be located in one or more of many places, such asthe posterior surface 96P of the optically transmissive structure,located opposite an anterior surface 96A of lens 96. The gap distance168 between the cornea and posterior surface 96P can be within a rangefrom about 1 to 10 mm, for example. The thickness 164 of the opticallytransmissive structure can be within a range from about 1 to 20 mm, forexample about 12 mm. A distance 162 from the distal lower surface of theobjective lens to the anterior surface 96A can be any suitable distance,for example within a range from about 10 mm to about 200 mm, for exampleabout 20 mm. In many embodiments, the patient interface assemblycomprises single use disposable structures to couple the opticallytransmissive structure comprising lens 96 to objective lens 94 andretention ring 97 of the patient interface assembly 14.

The patient interface assembly may comprise a support structure 14S inorder to place the optically transmissive structure to provide distance162 and distance 168 in combination with thickness 164. The supportstructure 14S may comprise a stiff support so as to resist movement ofthe optically transmissive structure and patient ring 97 when thepatient moves, for example. The support structure 14S may comprise anassembly of user combinable components such as retention ring 97, and adocking cone 14C, and an extension 14E, for example. The docking cone14C can receive the lens 96 of the conic extension section 14E, forexample.

Reference 180 location can be determined in one or more of many ways. Inmany embodiments, location 180 comprises an intersection of axis 99 withthe posterior surface 96P of the optically transmissive structure asdescribed herein. The location 180 may comprise a reference pointdetermined with axis 99. For example a location 180 can be located alongaxis 99 that intersects the posterior surface 96P based on the measuredsystem, and the location 180 may correspond to a distance of theposterior surface of the specific system lens as compared to the lowersurface of the generalized system. Alternatively, the location 180 maycomprise a distance from an internal structure of laser system 2 such asa mirror of the OCT system, or a distance from the surface of one of theobjective lenses such as the posterior surface of the achromaticobjective lens closest to the eye. The location of axis 99 can bedetermined based on system calibration, and the calibration may comprisedetermining a location of axis 99 that retro reflects the laser beam toa point of origin within system 2, for example. The axis 99 may comprisethe origin of the patient reference system 150, for example.

The deviation of the lower surface of a constructed system from thelocation of the generalized system can be determined and the values ofthe look up table determined accordingly.

The lens 96 may comprise a convexly curved posterior surface so as tourge gas bubbles to the periphery and away from the optical beam pathwhen the posterior surface 96P contacts a liquid interface fluid 96F,such one or more of water, saline, viscous fluid, or a viscoelasticfluid. The anterior surface 96A can be provided with a curved shape or aflat shape, for example. In many embodiments, the convexly curved lowersurface can extend the working range of the laser system so as toprovide optical breakdown over an increased range within the eye, forexample with combined corneal and cataract surgery. The dimensions oflens 96 can be determined so as to provide the extended range whenspaced apart from the cornea and combined with one or more doubletlenses by a person of ordinary skill in the art based on the teachingsdescribed herein. The negative lens of the z-telescope optics maycomprise radii of curvature to provide the extended range of opticalbreakdown when combined with the lens 96 and the one or more achromaticobjective lenses. The aberrations can be controlled over the intendedimaging and cutting volume of the eye and patient interface due to thebalancing of contributions from the z-telescope, the objective, and thecontact lens as a function of positions of the z-telescope, the X & Ygalvos, and the variation of placement and thickness of the contact lensby a person of ordinary skill in the art of lens design.

The lens 96 can be configured to provide a different change in thenumerical aperture of the beam focus than a flat plate, for example. Inmany embodiments, the lens 96 contributes a relatively small amount offocusing power when the laser beam is scanned near the cornea. However,when the laser beam is scanned at locations deeper in the eye, forexample near the lens capsule, the lens 96 can provide a greater effecton the beam focus than when the beam is focused near the cornea, so asto further change the numerical aperture of the laser beam, for example.

FIGS. 6B and 6C show side views and front views of structures of the eye43 as in FIG. 6A. The structures of the eye can be coupled to thepatient interface 52 for measurement and mapping with reference to theeye coordinate reference frame 150. The structures of the eye can bemapped from the eye coordinate reference system 150 to the machinecoordinate reference system 151 as described herein, for example. Theaxis 99 can be positioned in relation to one or more of many known axisof the eye such as the visual axis of the eye or the optical axis of theeye, for example.

The structures of the eye 43 that can be measured and mapped withrespect to eye coordinate reference system 150 include a cornea 43C,anterior chamber 43A, lens 43L, an iris 43I that defines a pupil of theeye, vitreous humor 43V and retina 43R. The lens 43L comprises acapsule, a cortex 43CX and a nucleus 43N. The capsule comprises ananterior capsule 43AC and a posterior capsule 43PC. Zonules 43Z of theeye 43 are coupled to the capsule of the eye. The structures of the eyecan be marked with the laser beam in order to calibrate the laser systemwith in situ calibration as described herein. Alternatively or incombination, the structures of the eye can be marked in order to trackthe eye and align the eye with the laser beam as described herein.

FIG. 7A shows a look up table 210 for an ultrafast (hereinafter “UF”)laser as described herein. The look up table 210 may comprise aplurality of discrete input values 212 over a range, for example fourvalues such as X, Y, Z of patient coordinate reference system anddistance CL of the lower surface of the lens, and a plurality of outputvalues 214. The X and Y values of the eye can range from −8 to 8 mm, in0.25 mm increments, for example. The Z value can range from 0 to 17 mmin 0.25 mm increments, for example. The CL value can range from −1 to 1mm in 0.5 mm increments, for example. These four dimensional inputvalues can be input into processor system and an output machine valueprovide for each combined input. The output values 214 of the look uptable can be provided as Xm, Ym and ZL for each combined input valuecombination. The output of Xm and Ym can each be within a range from−8.59 degrees to 8.59 degrees of the corresponding galvanometer mirror.The output value for ZL can be within a range from 3.7 to 20.7 mm, forexample. The total number of input and values of the LUT can be about1,457,625 for each input comprising (X, Y, Z, CL) and each outputcomprising (Xm, Ym, ZL), for example.

FIG. 7A1 shows an optical schematic of the components corresponding tothe look up table of FIG. 7A. The optical schematic shows the componentsas described herein used to determine the look up table for the UFpulsed laser, for example with reference to FIG. 4A. The laser beam canbe transmitted through zoom optics to a limiting aperture to determinebeam size. The limited beam proceeds to relay lenses and then to theoptical z-telescope lens. The distance ZL is varied, and ZL can beprogrammed into optical modeling software as described herein. The beamis then transmitted to X and Y galvos to deflect the beam passed to theobjective lenses (hereinafter “OBJ”). The objective lens focuses thelaser beam toward the optically transmissive structure, which maycomprise a plate or lens as described herein, for example. The distancefrom the objective lens to the optically transmissive structure(hereinafter “CLopt”) and be used to determine the location of theoptical breakdown, and the thickness of the optically transmissivestructure (hereinafter “WCL”) can be used to determine the location ofoptical breakdown.

FIG. 7A2 shows input and output of the look up table as in FIGS. 7A and7A1. The input parameters are the X, Y and Z locations of the opticalbreakdown within the mapped treatment volume, the distance from theobjective lens to the anterior surface of the optically transmissivestructure, and the thickness of the optically transmissive structure ofthe patient interface. The output of the look up table comprises the Xmirror position for the ultrafast laser (hereinafter “Xm(UF)”), the Ymirror position for the ultrafast laser (hereinafter “Ym(UF)”), and theposition of the z-telescope lens (hereinafter “ZL(UF)”).

FIG. 7A3 shows structure of the look up table via an excerpt of the lookup table as in FIGS. 7A and 7A1. The look up table comprises a header, abody and columns corresponding to the mapped coordinates of the systemas described herein. Although a low resolution is shown the table maycomprise a high resolution table readily constructed by a person ofordinary skill in the art based on the teachings described herein.

The header may comprise a description of the table and laser systemcomponents, for example. The header may comprise the input and outputparameters such as the output parameters Xm(UF) in degrees, Ym(UF) indegrees, ZL(UF) in mm, for the UF laser wavelength, and the header maycomprise the input parameters such as the X, Y and Z coordinates oftreatment in the eye in millimeters, the thickness of the opticallytransmissive structure CLth, and the position of the posterior surfaceof the optically transmissive structure CLopt,

The header may comprise baseline expected locations and coordinatereferences of identifiable structures, such as reference locations ofthe origin of the coordinate reference system, the location of thecornea along the Z axis, the location of the limbus along the X-axis andthe location of the limbus along the Y-axis. The mapped positions of thesystem components can be provided for each of these input locations,such as the X and Y mirror positions, Xm(UF), Ym(UF). Also included inthe header are the z-telescope position ZL(UF), The ZED(UF) position asshown in the figures, the delta Z value (hereinafter “Dz”) which maycomprise a correction, and the Strehl ratio which can be used todetermine the quality of beam focus and adjustment to the location ofoptical breakdown. One of the purposes of the header is to provide asample of key points within the look up table. These key points may becompared to multiple executions of the model to generate the look uptable. These key points can be used as watch points to gain an overviewof the performance of the model run and can be used to determine thehealth or veracity of the look up table.

The delta Z can be determined in one or more of many ways, and can bedetermined based on the computer modeling as described herein.Alternatively or in combination, the value of Delta Z can be determinebased on measurements of a constructed system as described herein, forexample.

The body of the look up table may contain the values of the look uptable. The values can be determined based on optical modeling asdescribed herein. Each value of the table may comprise Step comprising alocation of the record of the table, ZL, X, Y and Z coordinate, CLopt,CLth, Xm(UF), Ym (UF), ZL (UF), a value Dz at the location, the Strehlratio, and a flag. The flag may be indicative of the stability of themodel run in generating the look up table. Dz for example can be used asa metric as to whether the model adequately converges to a solution. Ingeneral, the generic look up table is automatically generated using anoptical program using a merit function and a set of variables to reducea custom designed error function. Dz is then calculated by the programusing a different mode or definition of best focus. Ideally these wouldarrive at the same solution but as the beam becomes more aberrated as afunction of position these two methods may differ as expressed in Dz.The flag can then be toggled to a set the value of Dz. For example, theflag may equal 1 when the Dz is with 10 um or 0.010 in the table of FIG.7A3 and set to 0 when outside this value. In this way, the automaticreading by system software of the look up table can using this value asan indication of the acceptable cut zone.

FIG. 7B shows a look up table 220 for an optical coherence tomographysystem. The look up table 220 may comprise a plurality of discrete inputvalues 222 over a range, for example four values such as X, Y, Z ofpatient coordinate reference system and distance CL of the lower surfaceof the lens, and a plurality of discrete output values 224. The X and Yvalues of the eye can range from −8 to 8 mm, in 0.25 mm increments, forexample. The Z value can range from 0 to 17 mm in 0.25 mm increments,for example. The CL value can range from −1 to 1 mm in 0.5 mmincrements, for example. These four dimensional input values can beinput into processor system and an output machine value provide for eachcombined input. The output values 224 of the look up table can beprovided as Xm, Ym and ZL for each combined input value combination. Theoutput of Xm and Ym can each be within a range from −8.59 degrees to8.59 degrees of the corresponding galvanometer mirror. The output valuefor ZL can be within a range from 3.7 to 20.7 mm, for example. Theoutput value of ZED of the OCT arm can be provided based on the teachingdescribed herein. The output value ZED can be configured to provideadjustment to the OCT arm over the full range of motion of thez-telescope moving lens in order to provide coherence to the OCT system,for example. The total number of input of the LUT can be about 1,457,625for each input comprising (X, Y, Z, CL) and each output comprising (Xm,Ym, ZL, ZED), for example. The output and input mapping process can beswitched. The OCT ranging system is a measurement device used to findintended surfaces. In this way, the values of OCT Xm, OCT Ym, OCT Zl,and ZED are determined once the targeted surface is located. These areused as input values to generate output values for X, Y, and Z for thelocation of the intended targeted structure. These output values for X,Y, Z along with measured values for CL can then be used as input to theUF LUT 212 to determine the output UF Xm, UF Ym, UF ZL for placing cuts.

FIG. 7B1 shows an optical schematic of the components corresponding tothe look up table of FIG. 7B. The optical schematic shows the componentsas described herein used to determine the look up table for the OCTsystem, for example with reference to FIG. 4A. The measurement beam canbe transmitted to a reference arm with a beam splitter. The portion ofthe beam transmitted through the beam splitter is transmitted to theoptical z-telescope lens. The distance ZL is varied, and ZL can beprogrammed into optical modeling software as described herein. The beamis then transmitted to X and Y galvos to deflect the beam passed to theobjective lenses OBJ. The objective lens focuses the laser beam towardthe optically transmissive structure, which may comprise a plate or lensas described herein, for example. The distance from the objective lensto the optically transmissive structure CLopt can be used to determinethe location of the measurement location corresponding to opticalbreakdown, and the thickness of the optically transmissive structure WCLcan be used similarly.

The OCT measurement may comprise an optical path length hereinafter(OPL) that can be referenced from one or more of many locations of theOCT measurement system, such as the output aperture from the lightsource of the OCT measurement beam.

FIG. 7B2 shows input and output of the look up table as in FIGS. 7B and7B1. The input parameters are the Xm, Ym and ZL locations of the OCTmeasurement beam within the mapped treatment volume, the distance fromthe objective lens to the anterior surface of the optically transmissivestructure CLopt, the thickness of the optically transmissive structureof the patient interface, CLth, and the location of measurement armZED(OCT). The output of the look up table comprises the X position forthe OCT measurement beam (hereinafter “X(OCT)”), the Y position for theOCT measurement beam (hereinafter “Y(OCT)”), and the Z position(hereinafter “Z(OCT)”) for the OCT measurement beam.

FIG. 7B3 shows structure of the look up table as in FIGS. 7B and 7B1.The look up table comprises a header, a body and columns correspondingto the mapped coordinates of the system as described herein. Although alow resolution is shown the table may comprise a high resolution tablereadily constructed by a person of ordinary skill in the art based onthe teachings described herein.

The header may comprise a description of the table and laser systemcomponents, for example. The header may comprise parameters such asXm(OCT) in degrees, Ym(OCT) in degrees, ZL(OCT) in mm, for the OCT laserwavelength, and the header may comprise the parameters such as the X, Yand Z coordinates of the measurement beam in the eye in millimeters, thethickness of the optically transmissive structure CLth, and the positionof the posterior surface of the optically transmissive structure CLoptfrom the posterior surface of the objective lens. One of the purposes ofthe header is to provide a sample of key points within the look uptable. These key points may be compared to multiple executions of themodel to generate the look up table. These key points can be used aswatch points to gain an overview of the performance of the model run andcan be used to determine the health or veracity of the look up table.

The header may comprise baseline locations and coordinate references ofidentifiable structures, such as reference locations of the origin ofthe coordinate reference system, the location of the cornea along the Zaxis, the location of the limbus along the X-axis and the location ofthe limbus along the Y-axis. The mapped positions of the systemcomponents can be provided for each of these locations, such as the Xand Y mirror positions, Xm(OCT), Ym(OCT). Also included in the headerare the z-telescope position ZL(OCT), the ZED(OCT) position as shown inthe figures, the delta Z value (hereinafter “Dz”) which may comprise acorrection, and the Strehl ratio which can be used to determine thequality of measurement beam focus.

The OCT delta Z can be determined in one or more of many ways, and canbe determined based on the computer modeling as described herein.Alternatively or in combination, the value of Delta Z can be determinebased on measurements of a constructed system as described herein, forexample. The value of the OCT delta Z may comprise a map from themeasured OCT location to the optical breakdown location, for example.

The body of the look up table may contain the values of the look uptable. The values can be determined based on optical modeling asdescribed herein. Each value of the table may comprise Step comprising alocation of the record of the table, ZL, X, Y and Z coordinate, CLopt,CLth, Xm(OCT), Ym (OCT), ZL (OCT), a value Dz at the location, theStrehl ratio, and a flag. The flag may be indicative of the stability ofthe model run in generating the look up table. Dz for example can beused as a metric as to whether the model adequately converges to asolution. In general, the generic look up table is automaticallygenerated using an optical program using a merit function and a set ofvariables to reduce a custom designed error function. Dz is thencalculated by the program using a different mode or definition of bestfocus. Ideally these would arrive at the same solution but as the beambecomes more aberrated as a function of position these two methods maydiffer as expressed in Dz. A flag can then be toggled to a set the valueof Dz. For example, the flag may equal 1 when the Dz is with 10 um or0.010 in the table of FIG. 7A3 and set to 0 when outside this value. Inthis way, the automatic reading by system software of the look up tablecan using this value as an indication of the acceptable cut zone.

FIG. 7C shows a look up table 230 for a video camera. The look up table230 may comprise a plurality of discrete input values 232 over a range,for example four values such as X, Y, Z of patient coordinate referencesystem and distance CL of the lower surface of the lens, and a pluralityof discrete output values 234. The X and Y values of the eye can rangefrom −9 to 9 mm, in 1 mm increments, for example. The Z value can rangefrom 6 to 10 mm in 1 mm increments, for example. The CL value can rangefrom −1 to 1 mm in 0.5 mm increments, for example. These fourdimensional input values can be input into processor system and anoutput machine value provide for each combined input. The output values234 of the look up table can be provided as Pixel X, Pixel Y, and therange of Pixel X and Pixel Y can each be from about −543 pixels to about543 pixels. The output and input mapping process can be switched. Thevideo system is a measurement device used to find intended surfaces. Thevideo system is also used as target aid for the user to place cuts. Inthese ways, the values of Pixel X and Pixel Y are determined using thevideo image. The values of Pixel X and Pixel Y along with eitherassumptions or measurements made for Z and CL are used as input valuesto generate output values for X, Y, and Z for the location of theintended targeted structure. The output values for X, Y, Z along withmeasured values for CL can then be used as input to the UF LUT 212 todetermine the output UF Xm, UF Ym, UF ZL for placing cuts.

The look up table 210, the look up table 220, the look up table 230 canbe combined in one or more of many ways to treat the patient. Further,inverse look up tables can be determined so as to map from machineparameters to parameter of the eye. In many embodiments, the OCT look uptable 220 is used to image the eye and patient interface with OCT at aseries of discrete OCT locations based on commands to the laser systemto in order to scan a target region of the eye. The scan data for thelocations of the eye can then be input into the look up table 210 fortreatment table generation and planning, and the patient treated withthe output 214 from treatment table 210.

The data for each look up table can be interpolated, for example withknown interpolation methods. For example, the interpolation may compriselinear interpolation based on values of closest neighbors provided tothe look up table. The look up table can be extrapolated to extend theranges.

The look up tables as described herein are provided in accordance withexamples, and a person of ordinary skill in the art will recognize manyalternatives and variations.

FIG. 7C1 shows an optical schematic of the components corresponding tothe look up table of FIG. 7C. The optical system forms an image on thecamera array comprising x pixels at x pixel locations (hereinafter “PixX”) and y pixels at y pixel locations (hereinafter Pix Y). The image isformed with a plurality of fixed focus lenses. The image beam passesthrough an aperture stop located between the fixed focus lenses toarrive at the sensor array. A field stop is provided along with anotherfixed focus lens optically coupled to the objective lenses. The patientinterface and distances are described herein.

FIG. 7C2 shows input and output of the look up table as in FIGS. 7C and7C1. The input comprises the measured Pix X and Pix Y coordinatereferences of the CCD array. The input may also comprise the Z focuslocation of the eye, and the CLopt and CLth parameters. The outputcomprises the X and Y coordinate references of the eye at the input Zdepth.

FIG. 7C3 shows the structure of the look up table as in FIGS. 7C to 7C2.Although a low resolution table is shown, the high resolution table canreadily be constructed by a person of ordinary skill in the art based onthe teachings described herein. The structure of the table comprises aheader and a body comprising columns of the table.

The header may comprise the input and output parameters for thewavelength of the video imaging system. The parameters may comprise theX, Y and Z locations of the imaging system within the eye and theparameters may comprise the corresponding X pixels (Pix X) and Y pixels(Pix Y). The header may comprise coordinate reference locationscorresponding to tissue structures of the eye, such as the iris or thelimbus, for example. The coordinate reference locations may comprise alocation within the eye along the axis of the system at coordinates X=0,Y=0 and Z=8 mm, for example. The corresponding mapped X and Y pixelcoordinates for X=5 mm and Y=5 mm can be provided at pixel coordinatelocations of approximately 303 pixels, respectively, for example. One ofthe purposes of the header is to provide a sample of key points withinthe look up table. These key points may be compared to multipleexecutions of the model to generate the look up table. These key pointscan be used as watch points to gain an overview of the performance ofthe model run and can be used to determine the health or veracity of thelook up table.

The body of the look up table may comprise the Pixel X, Pixel Y, Z,CLopt, Clth, input parameters. The output of the look up table maycomprise the output X and Y locations for each input record, forexample. The corresponding diameter of the spot can be provided at eachlocation in pixels, and a logic flag can be provided for each location.The logic flag may comprise one or more of many logic signals, and maycorrespond to whether the image of tissue is to be provided at thelocation, or whether the focus of the treatment beam at the mapped X Pixand Y Pix location is suitable for treatment, for example.

FIGS. 8A and 8B show marking of an eye in order to calibrate the eye inaccordance with many embodiments. FIG. 8A shows a side view of the eyeand FIG. 8B shows a front view of the eye. The eye is marked withreference to eye coordinate reference system 150 based on the machinecoordinate reference system as described herein. A mark 720 is made onthe eye with a laser beam. The eye is marked based on a targetedlocation 710. In many embodiments, the targeted location 710 differsfrom the marked location 720. The marked location 720 can be measuredwith the tomography system as described herein and compared to thetargeted location 710. The response to the difference between thetargeted location 710 and the marked location 720 the laser system canbe calibrated. The laser can be calibrated with in situ NC2 calibrationas described herein.

In many embodiments, the calibration of the mark with reference to thetargeted location 710 comprises a three dimensional calibration. The eyecoordinate reference system 150 comprises of three dimensionalcoordinate system and the difference between the targeted location 710and the marked location 720 comprises of three dimensional difference.In many embodiments, a second targeted location can be identified anddetermined in a second marked location can be identified and measuredwith respect to the second location. The second location may comprise anupdated, improved location based on the first measured targeted locationand the first measured mark.

The targeted location may comprise of plurality of targeted locationsand can be located in one or more of many places as described herein.For example, the targeted location may comprise a location of theoptically transmissive structure such as the lens 43L. The targetedlocation may comprise a location of the fluid 96F. The fluid 96F maycomprise a saline, a visco-elastic substance, or other viscous fluid asdescribed herein. In many embodiments, the visco-elastic fluid can bemarked and the visco-elastic fluid provides support so as to inhibitmovement between marking and measurement as described herein. Thetargeted location 710 may comprise of location of the cornea 43C or maycomprise a location of the interior chamber 43A. For example, thetargeted location may comprise a location of the lens 43L. For example,a posterior capsule of the lens 43PC, a cortex of the lens 43CX, or ananterior capsule of the lens 43AC as described herein, for example. Inmany embodiments of plurality of locations are targeted and a pluralityof marks are measured so as to provide three dimensional calibrationover a range of locations in order to ensure that the laser system isaccurately calibrated on the eye beam treated prior to initiating thetreatment pulses. The treatment pulses may comprise incision pulses, forexample, so as to incise an interior capsule of the lens 43L. Thetreatment pulses may comprise incision pulses so as to cut and resettissue of the lens 43L, for example, so as to cut the lens tissue suchas the cortex and the nucleus with a three dimensional profile thateffectively provides cubes of the lens or other structures of the lensthat can be readily removed. And in many embodiments, the plurality oftargeted locations are defined so as to define a volume and a portion ofthe volume comprises the treatment of the eye. For example, in manyembodiments, the calibration pulses may comprise targeted locations ofthe cornea or the anterior chamber or the viscous fluid 96F for example,and these anterior locations can be combined with posterior locations,for example, a portion of the lens so as to define a volume. And in manyembodiments, the targeted location comprises a single pulse at a singlelocation so as to define a mark with a single pulse. Alternatively or incombination, the marks may be defined with a plurality of laser beampulses at a targeted location, for example.

The targeted location of the eye for treatment may comprise the cornea43C. The cornea 43C can be treated in one or more of many ways, forexample with an incision so as to provide a refractive correction of thecornea 43C and the incisions of the cornea may comprise accessincisions, for example incisions to provide access for aphacoeemulsification probe, for example. And the incisions can beperformed with a plurality of laser beam pulses. The calibration isdescribed herein is particularly well-suited for incision of theposterior lens capsule and can provide improved accuracy so as toinhibit damage to structure posterior to the posterior capsule.

FIGS. 8C and 8D show a targeted location 730 and a mark 740 obtainedwith calibration as described herein. The targeted location 730coincides with the mark 740. The mark 710 may comprise one or more markssuch as a plurality of marks as described herein. The targeted location710 may comprise one or more targeted locations such as a plurality oftargeted locations as described herein. The mark 720 may comprise one ormore marks such as a plurality of marks as described herein.

The targeted location subsequent to NC2 calibration 730 may comprise oneor more targeted locations, for example a plurality of locations. Theone or more mark 740 obtained subsequent to calibration may comprise oneor more marks, for example a plurality of marks as described herein.

FIGS. 9A and 9B show a plurality of targeted locations on the eye and aplurality of corresponding on the eye for each of the plurality oftargeted locations. The plurality of targeted locations may comprise afirst targeted location 712, a second targeted location 714, a thirdtargeted location 716, and a fourth targeted location 718. A person ofordinary skill in the art will recognize that one or more of manytargeted locations can be used as described herein in one or more ofmany patterns. For example, square, circular, or other patterns can beused on the to provide the targeted location for the calibration andtracking as described herein. A plurality of marked locationscorresponding to the plurality of targeted locations can be identifiedand measured as described herein based on the difference between thetargeted locations and the measured locations of the marks, the lasersystem can be calibrated with NC2 calibration as described herein. Asshown in FIGS. 9A and 9B, the plurality of marks comprises a first mark722, a second mark 724, a third mark 726, and a fourth mark 728 in whicheach mark can be compared to each targeted location and the differencein the measured location of each mark compared to the measured locationof each targeted location so as to provide three dimensional calibrationover treatment volume as described herein. FIGS. 9C and 9D showrespectively side and front views of the eye subsequent to NC2calibration as described herein. The plurality of subsequent pulses canbe performed in order to determine the accuracy of the calibration withrespect to FIGS. 9A and 9B. For example, as shown in FIGS. 9C and 9D,the plurality of marks correspond quite closely to the plurality oftargeted locations. The acceptable tolerance can be defined in one ormore of many ways as described herein and can depend upon the tissuebeing treated with the laser beam. In many embodiments, the laser beamcalibration can be accurate to within about 10 microns, for example, andin many embodiments, to within about 100 microns for example. Theplurality of targeted locations comprises a first targeted location 732,a second targeted 734, a third targeted location 736, and a fourthtargeted location 738. A first plurality of marks comprises a first mark742, a second mark 744, a third mark 746, and a fourth mark 748. Theplurality of marks corresponds closely to the plurality targetedlocations and confirms the accuracy of the calibration.

The plurality of targeted locations can be defined in one or more ofmany ways. For example, the plurality of targeted locations subsequentto NC2 calibration as described herein, may comprise the originaltargeted locations. For example, the plurality of targeted locations 710comprising first targeted location 712, second targeted location 714,third targeted location 716, and fourth targeted location 718, maycomprise the targeted location subsequent to calibration, for examplefirst targeted location 732, second targeted location 734, thirdtargeted location 736, and fourth targeted location 738. In manyembodiments, the marks subsequent to NC2 calibration can be observed andmeasured to shift in relation to the marks prior to calibration of thelaser system.

FIGS. 10A and 10B show NC2 calibration of an eye at a plurality of depthso as to define a calibration volume in accordance with embodiments. Theplurality of targeted locations may comprise first targeted locations ofthe first axial depth along axis 99 and the second plurality oflocations along a second location of axis 99 so as to define a volume. Acalibration volume may comprise one or more locations of the treatmentso as to ensure the accuracy of the treatment in alignment of thetomography apparatus with the laser beam. The plurality of anteriortargeted locations and the plurality posterior targeted locations anddefine the volume in one or more of many ways is described herein.

The plurality of anterior targeted locations comprises first anteriortargeted location 712, second anterior targeted location 714, thirdanterior targeted location 716, fourth anterior targeted location 718.The plurality of posterior targeted locations comprises of firsttargeted location 713, a second targeted location 715, a third targetedlocation 717, and a fourth targeted location 719. The plurality ofanterior marks comprises a first anterior mark 722, a second anteriormark 724, a third anterior mark 726, and a fourth anterior mark 728. Theplurality of posterior marks comprises a first mark 723, a second mark725, a third mark 727, and a fourth mark 729.

The differences between the targeted locations in the marks can bemeasured to determine the accuracy of the laser system and to calibratethe laser system as described herein. For example, each of the anteriormarks can be compared to each of the anterior targeted locations andeach of the posterior marks can be compared to each of the posteriortargeted locations and the system calibrated in many embodiments thecalibration comprises a calibration volume and the laser systemcomprises mapping coordinate references that can be adjusted asdescribed herein so as to provide improved calibration. For example, thelook-up table as described herein can be adjusted. Alternativecombination calibration coefficients corresponding to the treatmentvolume can be adjusted.

The calibration can be tested based on the adjustments to thecalibration as described herein and additional pulses of the laser beamcan be used to form additional marks on the cornea. For example, thelaser beam can be pulsed at similar or the same targeted locations andthe motion of the laser beam marks can be observed and measured asdescribed herein. Subsequent to verification of the accuracy of thecalibration, the patient can be treated.

In many embodiments, the laser pulses can be measured in real time andcompared with the targeted locations with the tomography system asdescribed herein.

FIGS. 11A and 11B show targeted locations for calibration in the viscousfluid in the eye as described herein. In many embodiments, the anteriorlocation may comprise locations of the viscous fluid 96F as describedherein and the locations may comprise locations of a plurality ofstructures as described herein such as the visco-elastic fluid, thecornea, the anterior chamber, and the lens, for example. Work inrelation to embodiments also suggest that in some embodiments it may beappropriate to calibrate the system with pulses to the vitreous humor ofthe eye. For example, with pulses away from the posterior capsule of thelens and away from the protective outer structures of the vitreous humorin order to calibrate the system for example with a plurality ofindividual pulses approximately 1 millimeter beneath the posteriorcapsule, or example.

The plurality of anterior pulses comprises a first pulse 712, a secondpulse 714, a third pulse 716, and a fourth pulse 718. The plurality ofanterior targeted locations comprises a first anterior targeted location712, a second anterior targeted location 714, a third anterior targetedlocation 716, and a fourth anterior targeted location 718. The pluralityof posterior targeted locations comprises a first posterior targetedlocation 713, a second posterior targeted location 715, a thirdposterior targeted location 717, and a fourth posterior targetedlocation 719. The plurality of anterior marks comprises a first interiormark 722, a second interior mark 724, a third interior mark 726, and afourth interior 728. The plurality of posterior marks corresponding tothe plurality of posterior targeted locations comprises a firstposterior mark 723, a second posterior mark 725, a third posterior mark727, and a fourth posterior mark 729. The locations of each of the markscan be measured and compared with the targeted location and thecalibration co-efficient suggested as described herein. Alternatively orin combination, a treatment table may be adjusted in accordance withembodiments so as to provide improved accuracy.

Subsequent to calibration of the laser system, additional marks can beprovided as described herein for example, and the marks compared to thecalibration co-efficient in the targeted locations as described herein.FIGS. 12A and 12B show a calibration apparatus in accordance withembodiment. The calibration apparatus 300 comprises structures similarto structures of an eye. For example, the calibration apparatus 300comprises a container 350, the container 350 comprises of viscoussubstance similar viscous or solid substance that is opticallytransmissive similar to the structures of the eye. The material 320 maycomprise of visco-elastic fluid, a gel or other optically transmissivestructure and material, for example. The calibration apparatus 300comprises an iris structure 310, the iris structure comprises componentssimilar to an iris of an eye and can provide calibration with respect toa reference. In many embodiments the material 320 comprises a knownindex of refraction in order to calibrate the system, for example, theindex for refraction may comprise of a viscous material having a knownindex of refraction or a gel having a known index of refraction, forexample. Here, a structure or property is “similar” if it is within 10%,preferably within 5% and more preferably within about 1% of a typicalmeasurement of that structure or property in an adult human eye.

The calibration structure 300 may connect to the patient interface asdescribed herein and a fluid 96F can be provided above the calibrationapparatus, for example. The fluid 96F may comprise visco-elastic fluid,for example. A plurality of anterior marks can be made on thecalibration apparatus and a plurality of posterior marks can be made onthe calibration apparatus. For example, the anterior marks can be madein the fluid 96F, for example, a first targeted location, and a secondtargeted location, and a plurality of targeted locations as describedherein. A plurality of posterior marks can be made on the calibrationapparatus as described here.

In many embodiments, the calibration apparatus comprises an acoustictransducer 97A. The acoustic transducer 97A can be provided to measurethe energy required to provide optical breakdown and the laser systemcan be adjusted at a plurality of energy levels and swept and scannedthroughout the calibration volume to determine the energy required foroptical breakdown and the energy required for optical breakdown mappedacross the targeted treatment volume and calibration volume, forexample. In many embodiments, the treatment laser is adjusted to avolume substantially above the threshold energy in order to ensure thatoptical breakdown will occur at the targeted tissue. For example, asafety factor of a multiplier of 2× at least 1.5× and for example, 3×can be provided.

The calibration apparatus can be calibrated in manner and be used forcalibration in a manner similarly to that described above with referenceto the NC2 calibration of the eye as described herein. The calibrationapparatus may be used daily for example, or monthly, or for example,prior to the treatment of each patient, depending on the amount ofaccuracy required, for example.

The plurality of anterior locations comprises a first targeted location712, a second targeted location 714, a third targeted location 716, anda fourth targeted location 718. The plurality of posterior targetedlocations comprises a first targeted location 713, a second targetedlocation 715, a third targeted location 717, and a fourth targetedlocation 719. The plurality of anterior marks comprises a first anteriormark 722, a second anterior mark 724, a third anterior mark 726, and afourth anterior 728. The plurality of posterior targeted locations andcorresponding marks comprises a first posterior mark 723, a secondposterior mark 725, a fourth posterior mark 727, and a fifth posteriormark 729.

The plurality of targeted locations can be compared to the correspondingmarks and the calibration adjusted based on the marks of the calibrationapparatus as described herein.

Subsequent to calibration with the calibration apparatus, the laser canbe programmed to provide additional targeted locations and to providethe additional targeted locations and marks at the targeted locations toverify the calibration for example describe with reference to the NC2calibration of the eye as described herein. When the accuracy of thetreatment has been determined based on a suitable tolerance for thetreatment, the calibration apparatus can be removed from the patientinterface and the patient interface configured for surgery with thepatient.

FIGS. 13A and 13B show eye tracking in accordance with embodiments. FIG.13A shows a side view of the eye, FIG. 13B shows a front view of theeye. A plurality of marks 750 can be provided to track the eye duringsurgery in accordance with embodiments. The marks may comprise marksused for NC2 calibration, for example. Alternatively, the marks maycomprise marks provided specifically for calibration. A person ofordinary skill in the art will recognize many variations in accordancewith the embodiments described herein.

A plurality of marks for eye tracking may comprise a plurality ofbubbles and with respect to eye tracking a first location is shown and asecond location is shown of the mark in which the eye has moved. In manyembodiments, the location of the mark is measured and determined at oneor more locations for example, in the one or more locations can bestored in the processor memory and the tomography apparatus used tomeasure locations of the marks when the marks have moved, the lasersystem treatment can be adjusted accordingly and the adjustment maycomprise one or more of six degrees of freedom for example.

In many embodiments, the eye comprises six degrees of freedom, forexample three translational degrees of freedom and three rotationaldegrees of freedom. In many embodiments a plurality of marks can be usedso as to define an eye coordinate reference system that can be movableand adjusted with respect to the eye coordinate reference system 150 andthe treatment can be adjusted accordingly based on new coordinatereferences provided with the eye tracking system. In many embodimentsthe eye tracker provides reference measurements that can be used todetermine the position and orientation of the eye.

A first plurality of measured locations comprises a first measuredlocation 762, a second measured location 764, a third measured location766, and a fourth measured location 768. These measured locationscorrespond to a first position of the eye and a first orientation of theeye. These locations can be measured with the marks as described herein,when the eye comprises of first configuration. When the eye moves, andsubsequent to eye movement, as shown in FIGS. 13A and 13B, the measuredlocations of the marks changes, and the marks comprise a secondplurality of marked locations for example, a first measured marklocation 770, a second marked of plurality of marked locations. Themeasured locations for a particular measurement and location of the eyecomprises a marked location 770, a first marked location 772, a markedlocation 774, a marked location 776, and a marked location 778. Each ofthe marked locations can be compared to the plurality of measuredlocations and locations sorted in memory in the system.

The marked locations may comprise bubbles for example, or micro-bubblesfrom individual pulses of the laser beam and the pulses and thelocations of the pulses can be measured. When the eye moves, thetreatment can be adjusted in accordance with embodiments.

FIGS. 13A thru 13E show eye tracking in accordance with embodiments.FIGS. 13A and 13B show initial location of marks on the eye inaccordance with embodiments. FIGS. 13C and 13D show movement of themarks on the eye in relation to reference location in accordance withembodiments. FIG. 13E shows movement of eye reference frame 150 inaccordance with embodiments.

As shown in FIGS. 13A and 13B the eye can be marked with one or moremarks such as a plurality of marks, for example. The plurality of marksmay comprise a first mark 772, a second mark 774, a third mark 776 and afourth mark 778. The one or more marks may comprise one or more of themany marks and many locations as described herein. The marks are placedwith reference to eye coordinate reference system 150 and the marks maybe calibrated in accordance with the embodiments described herein. Theinitial location of the marks may comprise reference location so as toallow eye tracking.

The eye tracking as described herein can be used to track movement ofthe eye. The movement of the eye may correspond to at least one degreeof freedom, for example, as many as 6 degrees of freedom. In manyembodiments, the eye comprises 3 rotational degrees of freedom and 3translational degrees of freedom and the eye tracking embodiment asdescribed herein allow tracking of the eye for both movement andtranslation in many embodiments. FIGS. 13C and 13D show movement of theplurality of marks and the initial locations as described herein.

The plurality of locations generally comprises one or more locations andeach location corresponds to one or more marks. The plurality oflocations may comprise a first location 762, a second location 764, athird location 766 and a fourth location 768. The first location 762corresponds to the first mark 772, the second location 764 correspondsto the second mark 774, the third location 766 corresponds to the thirdmark 776, and the fourth location 768 corresponds to the fourth mark778.

Referring now to FIGS. 13C and 13D movement of the marks with respect tothe reference locations as shown in accordance with embodiments. Thefirst mark 772 has moved in relation to the first reference location762. The second mark 774 has moved in relation to the second referencelocation 764. The third mark 776 has moved in relation to the thirdreference location 766. And the fourth mark 778 has moved in relation tothe fourth reference location 768.

A relation to embodiments indicates that the number of marks andreference locations can be related to the number of degrees of freedomfor which eye tracking is provided. For example, a single mark canprovide translational references with respect to an X-Y plane, forexample, with relation to a pupil camera. Alternatively, 2 referencepoints can provide a rotation about an axis and 3 reference points canprovide 6 degrees of freedom—3 rotationally and 3 translationally. Thetomography apparatus can be used to measure the locations of the marksas described herein and the response to a measured location thetreatment can be adjusted.

FIG. 13E shows the eye coordinate reference system 150 and the moved eyecoordinate reference system 150M. In many embodiments, the eye can bemodeled as a substantially rigid body in which the movement of theplurality of marks can be used to determine movement of the eye. Thecoordinate reference system 150 comprises a first dimension 152, asecond dimension 154, and third dimension 156 as described herein. Themoved reference system 150M comprises a first dimension 152M, a seconddimension 154M, and a third reference dimension 156M. Dimension 152corresponds to dimension 152M which is moved. Dimension 154 correspondsto dimension 154M which is moved. Dimension 156 corresponds to Dimension156M of the moved reference frame. In addition to movement of the eyetranslationally about the 3 dimensions, the marks can be measured andused to determine rotations about one or more of the dimensions.Rotation about the first dimension 152 may comprise rotation 152R,rotation about the second dimension 154 may comprise rotation 154R, androtation about the third dimension 156 may comprise rotation 156R. Themovements can be provided as vectors both rotationally andtranslationally about one or more degrees of freedom, for example, 6degrees of freedom and the coordinate references can be transformed todetermine new locations for laser treatment.

The plurality of reference locations is shown in relation to theplurality of marks. For example, first mark 772 is shown in relation tothe first reference location 762. The second mark 774 is shown inrelation to the second reference location 764. The third mark 776 isshown in relation to the third reference location 766. The fourth mark778 is shown in relation to the fourth reference location 768. Therelationship of the reference locations to the marks can be used todetermine movement of the eye and the movement of the eye can be used todetermine movement of target locations of the eye for examplerotationally at a distance from the one or more marks. Thisdetermination of rotational and translational movement of the eyerelative to the marks will allow rotational and translationalcorrections of the targeted locations of the eye away from the marks,for example.

FIG. 14 shows a method of calibrating the system in accordance withembodiment. As a step 810, the system is calibrated in accordance withone or more steps of method 500 as described herein and a step 820, anoptically transmissive material is provided. The optically transmissivematerial may comprise an optically transmissive material of the eye orthe optically transmissive material may comprise an opticallytransmissive material of the calibration structure as described herein.At a step 830, one or more marks are generated and the opticallytransmissive material with the laser beam and one or more marks maycomprise a plurality of marks as described herein. At a step 840,locations of the marks are measured with the demography system asdescribed herein. At a step 850, the calibration of the laser isadjusted in response to locations of the mark for example with in situcalibration of an eye, the laser beam can be adjusted so that the targetlocations more closely match the intended location based on the targetedlocations. At a step 860, one or more verification marks are generatedas described herein. At a step 870, a patient is treated as describedherein.

FIG. 15 shows a method of eye tracking in accordance with embodiment. Ina step 910, an eye is provided. In a step 920, one or more marks arecreated on the eye as described herein. At a step 930, locations of themarks are measured as described herein. At a step 940, the locations ofthe marks are identified as reference locations. At a step 950, thelocations of the marks are measured as described herein. At a step 960,differences between the reference locations and the measured locationsare determined. At a step 970, the treatment is adjusted in response tothe differences between the reference locations and the locations of themarks as measured.

Examples of use of calibration methods described herein are presented asfollows. As shown in FIG. 16, an empirical approach for calibration1600, in accordance with many embodiments, may comprise the use of theoptics, including shared optics 50, of the system 2 to generate aninitial set of look up tables in a step 1610, linking real space pointsand their corresponding galvo parameters. In a step 1620, a galvolocation may be computed for a desired point. An example of a line inthat look up table may prescribe instructions to deliver a laser pulseat x=2 mm, y=3 mm and z=6 mm. In correspondence with these instructions,the x galvo may be rotated 1.8 deg, the y galvo may be rotated 3.1 deg,and the z galvo may be located at 13.6 mm, for instance. FIG. 7C3 showsfurther examples.

The calibration of initial look up tables may be performed by deliveringa laser pulse to a desired location (in a computed/desired XYZcoordinate system, for example) in a step 1630. Then, the interferometercan be used to locate where the point go in reality (i.e., the actuallocation in a real XYZ coordinate system) in a step 1640. Repeating thisoperation with a plurality of points, the initial look up table may bewarped to better match real and desired coordinates in a step 1650.

In very simple terms, the example calibration approach corrects fordepth in the look up table. For instance, if all the points are deep by10 μm, the initial look up tables may beadjusted so that the commanded zgalvo location will be correspondingly shallower.

In another example a 3d warp is applied to the look up tables defined bya 3-dimensional polynomial that may move, stretch, and rotate the lookup table. This may be a first degree polynomial warp but polynomials ofother degrees may be appropriate in at least some instances. Inexemplary embodiments, up to 16th degree polynomial warps may be used.Even greater degree polynomials may be used in further embodiments.

The above example calibration methods and steps may typically be done ina media with a similar index of refraction as that of an eye, such asgelatin. Then, an additional correction for the human lens index may beused.

Examples of use of motion tracking methods described herein arepresented as follows. Interferometer (OCT) images comprising informationof eye surfaces (e.g., cornea anterior and posterior, lens anterior andposterior, iris, limbus, etc.) may be analyzed and a mathematical modelof the eye may be constructed. This model may comprise one or more ofellipsoidal fits (e.g., with 9 parameters) for the cornea anterior andposterior, spherical fits (e.g., with 4 parameters) for the lensanterior and posterior, or 3-dimensionally oriented elliptical fits forthe iris and the limbus. In addition, the surface of the iris may befitted by a toroidal fit.

A plurality of locations (e.g., initial locations) in the eye may beselected for marking with micro incisions performed with the laser.Subsequent interferometer (OCT) readings of the marked areas may beanalyzed and the new location of the marks may be determined (newlocations). If some “eye motion” has occurred during the acquisition ofthe “initial locations” and the “new locations”, the two location maynot be the same.

The “eye motion” may be computed by assuming a mechanical model of theeye (e.g., viscoelastic material, elastic material, or rigid) andderiving the “eye motion” based on the “initial location” and “newlocation”. For example, a rigid eye model may be used. This model mayindicate that deformations of the eyeball may be neglected, so that anytwo points in the eye may always have the same distance under thisidealization. This idealization may be applicable to cases that thedeformations are expected to be small, such as ours.

Under the rigid body eye assumption, the mathematical eye model composedby the ellipsoids, spheres, 3-dimensional ellipses, and/or torus can betranslated and rotated according to the rigid body motion that may bedescribed as:Xnew_(i) =DX _(i)+Σ_(j)Rot_(ij) X _(j)

An “initial location” (X=x,y,z) may be rotated by the 3×3 rotationmatrix “Rot”. The resultant location may have added a translation vector(DX=dx,dy,dz) to provide the “new location”. In the above expression, aset of “initial locations” may be known and as may be the correspondingset of “new locations.” The three parameters (i.e., Euler angles) thatform the rotation matrix (Rot) and the three parameters that are in thetranslation vector (DX) may need to be found. The solution can beperformed by a regression method and the rigid body motion(translation-rotation transformation) may be defined.

This rigid body transformation may keep track of the current motion ofthe eye by means of performing the above process sequentially. Atreatment comprising a plurality of points that define a trajectory maythen be adjusted with the above formula to accurately target the newlocation.

In view of the above, a laser system to treat an object with a laserbeam in one embodiment comprises a laser to generate the laser beam, atomography system to generate a measurement beam and measure anoptically transmissive material of the object; an optical deliverysystem coupled to the laser and the tomography system to deliver thelaser beam and the measurement beam to the object; and a processorcoupled to the laser, the tomography system, and the optical deliverysystem, the processor comprising a tangible medium embodyinginstructions to: (1) place a mark on the object with the laser beam inresponse to a target location and, (2) measure a location of the markwith the measurement beam. The object may comprise one or more of aneye, an optically transmissive material, a gel, a liquid, a viscousmaterial, a solid optically transmissive material, or a fluid of apatient interface above the eye. The fluid of the patient interface maycomprise one or more of saline or viscoelastic fluid and wherein thefluid is marked with the laser beam.

The processor may comprise instructions to mark the eye at a pluralityof locations corresponding to a plurality of target locations, theplurality of locations comprising locations of one or more of a cornea,an aqueous humor, an iris, an anterior lens capsule, an anterior lenscapsule, a posterior lens capsule, a cortex, or a nucleus.

The processor may comprise instructions to mark the eye at the pluralityof locations prior to incising the eye with a plurality of laser beampulses to one or more of incise or treat the eye with the laser beampulses.

The plurality of marks may define a volume and the laser beam may bepulsed to incise the tissue are delivered at a plurality of locationswithin the volume. The volume may comprises at least a portion of atissue structure of the eye comprising one or more of a tear film, acornea, an aqueous humor, an iris, an anterior lens capsule, theposterior lens capsule, a lens cortex, a lens nucleus, a vitreous humor,a Berger's space, or an anterior hyaloid membrane of the vitreous humor.

The processor may comprise instructions to identify a correspondingtarget location for each of the plurality of marks measured with thetomography system and compare the corresponding target location with themeasured location for each of the plurality of marks in order todetermine one or more of calibration or eye position.

The tissue structure of the eye may comprise a plurality of tissuestructures, each of the plurality of tissue structures having adifferent index of refraction for the laser beam than another of theplurality of tissue structures, and wherein each tissue structurecomprises a first index of refraction for the laser beam and a secondindex of refraction for a measurement beam of the tomography system, thefirst index of refraction different from the second index of refraction,and wherein the laser beam and measurement beam comprise one or morewavelengths of light different from each other.

The processor may comprise instructions to compare the location of themark with the target location and calibrate the laser in response to thelocation of the mark and the targeted location of the mark.

The processor may comprise instructions to perform in situ calibrationto correct for drift of an optical delivery system to deliver the laserbeam to the object.

The processor may comprise instructions to perform a daily calibrationto correct for drift of an optical delivery system to deliver the laserbeam to the object.

The processor may comprise instructions to adjust one or more machineparameters related to one or more of the laser, the optical deliverysystem, or the tomography system in response to a comparison of thecorresponding target location with measured location for said each ofthe plurality of marks in order to calibrate the laser system.

The processor may comprise instructions to track the object in responseto the measured location of the mark.

The processor may comprise instructions to adjust positions of the laserbeam pulses in response to a comparison of the corresponding targetlocation with measured location for said each of the plurality of marksin order to track and correct for eye movement with the laser system.

The location of each of the plurality of marks may be compared with aprior location of said each of the plurality of marks in order todetermine movement of the eye.

The plurality of marks may comprise three or more marks and wherein themovement of the eye comprises rotation of the eye around one or moredimensions of a coordinate reference system of the eye, and wherein thetreatment is adjusted in response to translation along the one or moredimensions, and wherein the movement of the eye comprises translation ofthe eye along one or more dimensions of the coordinate reference systemof the eye and wherein the treatment is adjusted in response totranslation along the one or more dimensions.

The one or more dimensions may comprise three dimensions, wherein thetreatment is adjusted in response to rotation around the threedimensions and translation along the three dimensions and the opticallytransmissive material may comprise a plurality of optically transmissivestructures having a plurality of indices of refraction, and thepositions of laser beam pulses to treat one or more of the opticallytransmissive structures may be adjusted in response to locations of theoptically transmissive structures having the plurality of indices ofrefraction.

The processor may comprise instructions to mark the material in each ofthe optically transmissive structures to define a volume comprising theplurality of optically transmissive structures having the plurality ofindices of refraction.

The processor may comprise instructions to mark the material in a firstof the optically transmissive structures and to adjust positions of thelaser beam pulses for treatment in a second of the opticallytransmissive structures without placing marks for tracking in the secondof the optically transmissive structures, the second of the plurality ofoptically transmissive structures comprising an index of refractiondifferent than the index of refraction of the first of the opticallytransmissive structures.

The processor may comprise instructions to mark the material with one ormore bubbles, and the processor may comprise instructions to correct foroptical aberrations in response to locations of the one or more bubbles.

The tomography system may comprise one or more of an optical coherencetomography system, a spectral domain optical coherence tomographysystem, a time domain optical coherence tomography system, a Scheimpflugtomography system, a confocal tomography system, or a low coherencereflectometry system.

The laser system may further comprise an acoustic transducer to detectoptical breakdown in response to an amount of energy of the laser beam.

A method of treating an object with a laser beam comprises placing amark on the object in response to a target location; and measuring alocation of the mark with a measurement beam. The method may furthercomprise incising the eye with a plurality of laser beam pulses to oneor more of incise or treat the eye with the laser beam pulses subsequentto placing the mark on the object. The method may further compriseidentifying a corresponding target location for each of the plurality ofmarks measured with the tomography system and comparing thecorresponding target location with the measured location for each of theplurality of marks in order to determine one or more of calibration oreye position. The method may further comprise comparing the location ofthe mark with the target location and calibrating the laser in responseto the location of the mark and the targeted location of the mark.

The laser beam is generated by a laser. The laser beam and themeasurement beam are delivered by an optical delivery system. The objectmay comprise one or more of an eye, an optically, a calibrationapparatus comprising transmissive material, a gel, a liquid, a viscousmaterial, a solid optically transmissive material, or a fluid of apatient interface above the eye. The fluid of the patient interface maycomprise one or more of saline or viscoelastic fluid and wherein thefluid is marked with the laser beam.

The measurement beam may be generated by a tomography system. Thetomography system may comprise one or more of an optical coherencetomography system, a spectral domain optical coherence tomographysystem, a time domain optical coherence tomography system, a Scheimpflugtomography system, a confocal tomography system, or a low coherencereflectometry system.

Placing the mark on the object in response to a target location maycomprise marking the eye at a plurality of locations corresponding to aplurality of target locations, the plurality of locations comprisinglocations of one or more of a cornea, an aqueous humor, an iris, ananterior lens capsule, an anterior lens capsule, a posterior lenscapsule, a cortex or a nucleus.

Marking the eye at the plurality of locations may comprise defining avolume, and wherein laser beam pulses to incise the tissue are deliveredat a plurality of locations within the volume. The volume may compriseat least a portion of a tissue structure of the eye comprising one ormore of a tear film, a cornea, an aqueous humor, an iris, an anteriorlens capsule, the posterior lens capsule, a lens cortex, a lens nucleus,a vitreous humor, a Berger's space, or an anterior hyaloid membrane ofthe vitreous humor.

The tissue structure of the eye may comprise a plurality of tissuestructures, each of the plurality of tissue structures having adifferent index of refraction for the laser beam than another of theplurality of tissue structures and wherein each tissue structurecomprises a first index of refraction for the laser beam and a secondindex of refraction for a measurement beam of the tomography system, thefirst index of refraction different from the second index of refraction,and wherein the laser beam and measurement beam comprise one or morewavelengths of light different from each other.

The method may further comprise performing in situ calibration tocorrect for drift of an optical delivery system to deliver the laserbeam to the object.

The method may further comprise performing a daily calibration tocorrect for drift of an optical delivery system to deliver the laserbeam to the object.

The method may further comprise adjusting one or more machine parametersrelated to one or more of the laser, the optical delivery system, or thetomography system in response to a comparison of the correspondingtarget location with measured location for said each of the plurality ofmarks in order to calibrate the laser system.

The method may further comprise tracking the object in response to themeasured location of the mark.

The method may further comprise adjusting positions of the laser beampulses in response to a comparison of the corresponding target locationwith measured location for said each of the plurality of marks in orderto track and correct for eye movement with the laser system.

The location of each of the plurality of marks may be compared with aprior location of said each of the plurality of marks in order todetermine movement of the eye. The plurality of marks may comprise threeor more marks. The movement of the eye may comprise rotation of the eyearound one or more dimensions of a coordinate reference system of theeye, and wherein the treatment is adjusted in response to translationalong the one or more dimensions, and the movement of the eye maycomprise translation of the eye along one or more dimensions of thecoordinate reference system of the eye and wherein the treatment isadjusted in response to translation along the one or more dimensions.The one or more dimensions may comprise three dimensions, and thetreatment may be adjusted in response to rotation around the threedimensions and translation along the three dimensions. The opticallytransmissive material may comprise a plurality of optically transmissivestructures having a plurality of indices of refraction and whereinpositions of laser beam pulses to treat one or more of the opticallytransmissive structures are adjusted in response to locations of theoptically transmissive structures having the plurality of indices ofrefraction.

The method may further comprise marking the material in each of theoptically transmissive structures to define a volume comprising theplurality of optically transmissive structures having the plurality ofindices of refraction.

The method may further comprise marking the material in a first of theoptically transmissive structures and adjusting positions of the laserbeam pulses for treatment in a second of the optically transmissivestructures without placing marks for tracking in the second of theoptically transmissive structures, the second of the plurality ofoptically transmissive structures comprising an index of refractiondifferent than the index of refraction of the first of the opticallytransmissive structures.

The method may further comprise marking the material with one or morebubbles and correcting for optical aberrations in response to locationsof the one or more bubbles.

The method may further comprise detecting optical breakdown in responseto an amount of energy of the laser beam with an acoustic transducer.

A system to treat an eye with a laser beam, the system comprises a laserto generate the laser beam, a measurement system configured to measurefirst and second optically transmissive materials having differingindices of refraction;

an optical delivery system coupled to the laser to deliver the laserbeam to the material second material through the first material; and aprocessor coupled to the measurement system and the optical deliverysystem, the processor configured to form a mark in the material with thelaser beam per a target location, to measure a location of the mark withthe measurement system, to calibrate the system by comparing the targetlocation and the measured location of the mark using the indices ofrefraction, and to direct the beam toward a treatment target within theeye with the calibrated system.

While preferred embodiments of the present disclosure have been shownand described herein, it will be obvious to those skilled in the artthat such embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will be apparent to those skilledin the art without departing from the scope of the present disclosure.It should be understood that various alternatives to the embodiments ofthe present disclosure described herein may be employed withoutdeparting from the scope of the present invention. Therefore, the scopeof the present invention shall be defined solely by the scope of theappended claims and the equivalents thereof.

What is claimed is:
 1. A laser system to treat an eye with a laser beam,comprising: a laser to generate the laser beam; a tomography system togenerate a measurement beam and measure at least one surface of thestructure of the eye; an optical delivery system coupled to the laserand the tomography system to deliver the laser beam and the measurementbeam to the eye; a memory storing therein a look-up table, thelook-table including first data which maps locations within the eye toone or more control parameters for the laser, and further includingsecond data which maps the locations within the eye to one or morecontrol parameters for the tomography system; and a processor coupled tothe laser, the tomography system, and the optical delivery system, theprocessor comprising a tangible medium embodying instructions to: inresponse to the first data in the look-up table, mark the eye at one ormore mark locations corresponding to each of one or more targetlocations, the one or more target locations being disposed at of one ormore of a cornea, an aqueous humor, an iris, an anterior lens capsule,an anterior lens capsule, a posterior lens capsule, a cortex, or anucleus, in response to the second data in the look-up table, measurewith the measurement beam a measured location for each of the one ormore marks, and compare the corresponding target location with themeasured location for each of the one or more marks in order todetermine one or more of calibration of the laser system or eyeposition.
 2. The laser system of claim 1, wherein the processorcomprises instructions to mark the eye at a plurality of mark locations.3. The laser system of claim 2, wherein the processor comprisesinstructions to mark the eye at the plurality of mark locations prior toincising the eye with a plurality of laser beam pulses to one or more ofincise or treat the eye with the laser beam pulses.
 4. The laser systemof claim 2, wherein the plurality of marks define a volume and whereinlaser beam pulses to incise the tissue are delivered at a plurality oflocations within the volume.
 5. The laser system of claim 4, wherein theprocessor comprises instructions to identify a corresponding targetlocation for each of the plurality of marks measured with the tomographysystem and wherein the processor comprises instructions to compare thecorresponding target location with the measured location for each of theplurality of marks in order to determine one or more of calibration oreye position.
 6. The laser system of claim 4, wherein the volumecomprises at least a portion of a tissue structure of the eye comprisingone or more of a tear film, a cornea, an aqueous humor, an iris, ananterior lens capsule, the posterior lens capsule, a lens cortex, a lensnucleus, a vitreous humor, a Berger's space, or an anterior hyaloidmembrane of the vitreous humor.
 7. The laser system of claim 6, whereinthe tissue structure of the eye comprises a plurality of tissuestructures, each of the plurality of tissue structures having adifferent index of refraction for the laser beam than another of theplurality of tissue structures, and wherein each tissue structurecomprises a first index of refraction for the laser beam and a secondindex of refraction for a measurement beam of the tomography system, thefirst index of refraction different from the second index of refraction,and wherein the laser beam and measurement beam comprise one or morewavelengths of light different from each other.
 8. A laser system,comprising: a laser to generate a laser beam; a tomography system togenerate a measurement beam and measure an optically transmissivematerial of an object selected from the group consisting of an eye, afluid of a patient interface above the eye and a calibration apparatuscomprising one or more structures similar to a structures of the eye; anoptical delivery system coupled to the laser and the tomography systemto deliver the laser beam and the measurement beam to the object; amemory storing therein a look-up table, the look-table including firstdata which maps locations within the object to one or more controlparameters for the laser, and further including second data which mapsthe locations within the object to one or more control parameters forthe tomography system; and a processor coupled to the laser, thetomography system, and the optical delivery system, the processorcomprising a tangible medium embodying instructions to: in response tothe first data in the look-up table, place a mark on the object with thelaser beam in response to a target location and, in response to thesecond data in the look-up table, measure a location of the mark withthe measurement beam, and compare the location of the mark with thetarget location and calibrate the laser in response to the location ofthe mark and the targeted location of the mark.
 9. The laser system ofclaim 8, wherein the processor comprises instructions to perform in situcalibration to correct for drift of an optical delivery system todeliver the laser beam to the object.
 10. The laser system of claim 8,wherein the processor comprises instructions to perform a dailycalibration to correct for drift of an optical delivery system todeliver the laser beam to the object.
 11. The laser system of claim 8,wherein the processor comprises instructions to adjust one or moremachine parameters related to one or more of the laser, the opticaldelivery system, or the tomography system in response to a comparison ofthe corresponding target location with measured location for said eachof the plurality of marks in order to calibrate the laser system. 12.The laser system of any one of the preceding claims, wherein theprocessor comprises instructions to track the object in response to themeasured location of the mark.
 13. The laser system of claim 12, whereinthe processor comprises instructions to adjust positions of the laserbeam pulses in response to a comparison of the corresponding targetlocation with measured location for said each of the plurality of marksin order to track and correct for eye movement with the laser system.14. The laser system of claim 13, wherein the location of each of theplurality of marks is compared with a prior location of said each of theplurality of marks in order to determine movement of the eye.
 15. Thelaser system of claim 14, wherein the plurality of marks comprises threeor more marks and wherein the movement of the eye comprises rotation ofthe eye around one or more dimensions of a coordinate reference systemof the eye, and wherein the treatment is adjusted in response totranslation along the one or more dimensions, and wherein the movementof the eye comprises translation of the eye along one or more dimensionsof the coordinate reference system of the eye and wherein the treatmentis adjusted in response to translation along the one or more dimensions.16. The laser system of claim 15, wherein the one or more dimensionscomprises three dimensions, and wherein the treatment is adjusted inresponse to rotation around the three dimensions and translation alongthe three dimensions and wherein the optically transmissive materialcomprises a plurality of optically transmissive structures having aplurality of indices of refraction and wherein positions of laser beampulses to treat one or more of the optically transmissive structures areadjusted in response to locations of the optically transmissivestructures having the plurality of indices of refraction.
 17. The lasersystem of claim 16, wherein the processor comprises instructions to markthe material in each of the optically transmissive structures to definea volume comprising the plurality of optically transmissive structureshaving the plurality of indices of refraction.
 18. The laser system ofclaim 16, wherein the processor comprises instructions to mark thematerial in a first of the optically transmissive structures and toadjust positions of the laser beam pulses for treatment in a second ofthe optically transmissive structures without placing marks for trackingin the second of the optically transmissive structures, the second ofthe plurality of optically transmissive structures comprising an indexof refraction different than the index of refraction of the first of theoptically transmissive structures.
 19. The laser system of claim 1,wherein the processor comprises instructions to mark the material withone or more bubbles, and wherein the processor comprises instructions tocorrect for optical aberrations in response to locations of the one ormore bubbles.
 20. The laser system of claim 1, wherein the tomographysystem comprises one or more of an optical coherence tomography system,a spectral domain optical coherence tomography system, a time domainoptical coherence tomography system, a Scheimpflug tomography system, aconfocal tomography system, or a low coherence reflectometry system. 21.The laser system of claim 1, further comprising an acoustic transducerto detect optical breakdown in response to an amount of energy of thelaser beam.
 22. The laser system of claim 1, further comprising a videosystem configured to display an image of the eye, wherein the look-uptable further comprises third data the locations within the eye to pixellocations of the image.
 23. The laser system of claim 8, furthercomprising a video system configured to display an image of the object,wherein the look-up table further comprises third data the locationswithin the object to pixel locations of the image.
 24. A method oftreating an eye with a laser beam with a laser system which includes alaser and a tomography system, the method comprising: storing in amemory a look-up table, the look-table including first data which mapslocations within the eye to one or more control parameters for the laserand further including second data which maps the locations within theeye to one or more control parameters for the tomography system;generating the laser beam with the laser; using the tomography system togenerate a measurement beam and to measure at least one surface of astructure of the eye; delivering the laser beam and the measurement beamto the eye via an optical delivery system coupled to the laser and thetomography system; in response to the first data in the look-up table,marking the eye at one or more mark locations corresponding to each ofone or more target locations, the one or more target locations beingdisposed at of one or more of a cornea, an aqueous humor, an iris, ananterior lens capsule, an anterior lens capsule, a posterior lenscapsule, a cortex, or a nucleus; in response to the second data on thelook-up table, measuring with the measurement beam a measured locationfor each of the one or more marks; and comparing the correspondingtarget location with the measured location for each of the one or moremarks in order to determine one or more of calibration of the lasersystem or eye position.